What is the bug or the crash?

In a project I have made settings in the layer properties Check Geometry Is Valid

If I then digitize a normal feature and press save. All good.
If I digitize a feature with illegal geometry I get a warning - as expected.
Then I delete the feature - and try to save. Then I get a warning - unable to save

In earlier versions I have been able to make a Fix geometries (using multipolygon or multiline). Now Unable to solve using Fix geometry

It seems the digitizing an illegal feature and deleting, it is still in the cash...
This bug make it almost impossible to digitize.

All my students have the same issue on different platforms same QGIS version.

Steps to reproduce the issue

In a layer set properties - Check Geometry is Valid
Digitize a nomal feature - Save
Digitize an illegal feature - Save
Delete the feature.
Digitize a new feature - Save

Versions

3.40.0 Windows and Mac

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response