diff --git a/deps/rabbit/src/mc_amqp.erl b/deps/rabbit/src/mc_amqp.erl
index 0975f65c57be..63f6e37e5eb9 100644
--- a/deps/rabbit/src/mc_amqp.erl
+++ b/deps/rabbit/src/mc_amqp.erl
@@ -50,6 +50,29 @@
                               Val :: term()}].
 -type opt(T) :: T | undefined.
 
+%% This representation was used in v3.13.7. 4.x understands this record for
+%% backward compatibility, specifically for the rare case where:
+%% 1. a 3.13 node internally parsed a message from a stream via
+%% ```
+%% Message = mc:init(mc_amqp, amqp10_framing:decode_bin(Bin), #{})
+%% ```
+%% 2. published this Message to a queue
+%% 3. RabbitMQ got upgraded to 4.x
+%%
+%% This record along with all its conversions in this module can therefore
+%% be deleted in some future RabbitMQ version once it's safe to assume that
+%% these upgraded messages have all been consumed.
+-record(msg,
+        {
+         header :: opt(#'v1_0.header'{}),
+         delivery_annotations = []:: list(),
+         message_annotations = [] :: list(),
+         properties :: opt(#'v1_0.properties'{}),
+         application_properties = [] :: list(),
+         data = [] :: amqp10_data(),
+         footer = [] :: list()
+        }).
+
 %% This representation is used when the message was originally sent with
 %% a protocol other than AMQP and the message was not read from a stream.
 -record(msg_body_decoded,
@@ -97,7 +120,7 @@
          body_code :: body_descriptor_code()
         }).
 
--opaque state() :: #msg_body_decoded{} | #msg_body_encoded{} | #v1{}.
+-opaque state() :: #msg{} | #msg_body_decoded{} | #msg_body_encoded{} | #v1{}.
 
 -export_type([state/0]).
 
@@ -128,6 +151,8 @@ convert_from(?MODULE, Sections, _Env) when is_list(Sections) ->
 convert_from(_SourceProto, _, _Env) ->
     not_implemented.
 
+convert_to(?MODULE, Msg = #msg{}, _Env) ->
+    convert_from_3_13_msg(Msg);
 convert_to(?MODULE, Msg, _Env) ->
     Msg;
 convert_to(TargetProto, Msg, Env) ->
@@ -139,7 +164,22 @@ size(#v1{message_annotations = MA,
                    [] -> 0;
                    _ -> ?MESSAGE_ANNOTATIONS_GUESS_SIZE
                end,
-    {MetaSize, byte_size(Body)}.
+    {MetaSize, byte_size(Body)};
+%% Copied from v3.13.7.
+%% This might be called in rabbit_fifo_v3 and must therefore not be modified
+%% to ensure determinism of quorum queues version 3.
+size(#msg{data = Body}) ->
+    BodySize = if is_list(Body) ->
+                      lists:foldl(
+                        fun(#'v1_0.data'{content = Data}, Acc) ->
+                                iolist_size(Data) + Acc;
+                           (#'v1_0.amqp_sequence'{content = _}, Acc) ->
+                                Acc
+                        end, 0, Body);
+                  is_record(Body, 'v1_0.amqp_value') ->
+                      0
+               end,
+    {_MetaSize = 0, BodySize}.
 
 x_header(Key, Msg) ->
     message_annotation(Key, Msg, undefined).
@@ -151,6 +191,10 @@ property(_Prop, #msg_body_encoded{properties = undefined}) ->
     undefined;
 property(Prop, #msg_body_encoded{properties = Props}) ->
     property0(Prop, Props);
+property(_Prop, #msg{properties = undefined}) ->
+    undefined;
+property(Prop, #msg{properties = Props}) ->
+    property0(Prop, Props);
 property(_Prop, #v1{bare_and_footer_properties_pos = ?OMITTED_SECTION}) ->
     undefined;
 property(Prop, #v1{bare_and_footer = Bin,
@@ -298,7 +342,9 @@ protocol_state(#v1{message_annotations = MA0,
                                                     ttl = Ttl}, Anns),
     MA = protocol_state_message_annotations(MA0, Anns),
     Sections = to_sections(Header, MA, []),
-    [encode(Sections), BareAndFooter].
+    [encode(Sections), BareAndFooter];
+protocol_state(#msg{} = Msg, Anns) ->
+    protocol_state(convert_from_3_13_msg(Msg), Anns).
 
 prepare(read, Msg) ->
     Msg;
@@ -322,7 +368,9 @@ prepare(store, #msg_body_encoded{
         bare_and_footer_application_properties_pos = AppPropsPos,
         bare_and_footer_body_pos = BodyPos,
         body_code = BodyCode
-       }.
+       };
+prepare(store, Msg = #msg{}) ->
+    Msg.
 
 %% internal
 
@@ -379,7 +427,9 @@ msg_to_sections(#v1{message_annotations = MAC,
                    Sections = amqp10_framing:decode_bin(Bin),
                    Sections ++ [{amqp_encoded_body_and_footer, BodyAndFooterBin}]
            end,
-    to_sections(undefined, MAC, Tail).
+    to_sections(undefined, MAC, Tail);
+msg_to_sections(#msg{} = Msg) ->
+    msg_to_sections(convert_from_3_13_msg(Msg)).
 
 to_sections(H, MAC, P, APC, Tail) ->
     S0 = case APC of
@@ -410,6 +460,20 @@ to_sections(H, MAC, Tail) ->
             [H | S]
     end.
 
+convert_from_3_13_msg(#msg{header = H,
+                           delivery_annotations = _,
+                           message_annotations = MAC,
+                           properties = P,
+                           application_properties = APC,
+                           data = Data,
+                           footer = FC}) ->
+    #msg_body_decoded{header = H,
+                      message_annotations = MAC,
+                      properties = P,
+                      application_properties = APC,
+                      data = Data,
+                      footer = FC}.
+
 -spec protocol_state_message_annotations(amqp_annotations(), mc:annotations()) ->
     amqp_annotations().
 protocol_state_message_annotations(MA, Anns) ->
@@ -482,11 +546,14 @@ message_annotation(Key, State, Default)
 
 message_annotations(#msg_body_decoded{message_annotations = L}) -> L;
 message_annotations(#msg_body_encoded{message_annotations = L}) -> L;
-message_annotations(#v1{message_annotations = L}) -> L.
+message_annotations(#v1{message_annotations = L}) -> L;
+message_annotations(#msg{message_annotations = L}) -> L.
 
 message_annotations_as_simple_map(#msg_body_encoded{message_annotations = Content}) ->
     message_annotations_as_simple_map0(Content);
 message_annotations_as_simple_map(#v1{message_annotations = Content}) ->
+    message_annotations_as_simple_map0(Content);
+message_annotations_as_simple_map(#msg{message_annotations = Content}) ->
     message_annotations_as_simple_map0(Content).
 
 message_annotations_as_simple_map0(Content) ->
@@ -501,6 +568,9 @@ message_annotations_as_simple_map0(Content) ->
 application_properties_as_simple_map(
   #msg_body_encoded{application_properties = Content}, L) ->
     application_properties_as_simple_map0(Content, L);
+application_properties_as_simple_map(
+  #msg{application_properties = Content}, L) ->
+    application_properties_as_simple_map0(Content, L);
 application_properties_as_simple_map(
   #v1{bare_and_footer_application_properties_pos = ?OMITTED_SECTION}, L) ->
     L;