PostGIS layer saved in 3.10 project, fail to load correctly on 3.14

[SrNetoChan]

Describe the bug

When using postgis tables where the geometry type is not restricted geometry(Geometry,4326) , if you have used DBmanager in QGIS 3.10 to load the table in different geometry types and save the project, once you try to open the same project in QGIS 3.14, it will fail to load the layers. This is, in my opinion, a severe regression that can break lots of projects.

Besides, fixing the failing layers is almost impossible because the layers fro each geometry won't show on the browser unless the option Don't resolve type of unrestricted columns (GEOMETRY) in the connection is disabled AND there is at leas one feature of the wanted geometry type already.

How to Reproduce

1. Create a table with an unrestricted geometry type

CREATE TABLE tests (
gid serial primary key,
geom geometry(Geometry, 4326)
);

2. In QGIS 3.10 LTR, using DBManager, load the table for the 3 geometry types
3. Save the project
4. Load the project in QGIS 3.14, those layers should fail to load.

QGIS and OS versions

Additional context

[elpaso]

Can you please attach a sample project (with localhost connection is ok, I will edit the project to use my local connection if needed).

[SrNetoChan]

I will create one ASAP.

[SrNetoChan]

@elpaso heres a project with that problem. It was created in QGIS 3.10.

The database is called gisdb, and you can create the table using:

CREATE TABLE tests (
gid serial primary key,
geom geometry(Geometry, 4326)
);

dbmanager_unrestricted_geom.zip