diff --git a/_release-content/migration-guides/removed_PositionedGlyph_byte_index_and_byte_length.md b/_release-content/migration-guides/removed_PositionedGlyph_byte_index_and_byte_length.md
new file mode 100644
index 0000000000000..2a50b72fd42b7
--- /dev/null
+++ b/_release-content/migration-guides/removed_PositionedGlyph_byte_index_and_byte_length.md
@@ -0,0 +1,8 @@
+---
+title: "`PositionedGlyph`'s `byte_index` and `byte_length` fields have been removed"
+pull_requests: [23695]
+---
+
+`PositionedGlyph`'s `byte_index` and `byte_length` fields have been removed. Unlike Cosmic Text, `Parley` doesn't expose these values in its `GlyphRun`s.
+
+If needed, these range can be retrieved using `visual_clusters` by mapping each cluster's `text_range` to its corresponding `Glyph`(s). However, this approach is quite fragile.