Error messages are not consistent anymore when login with a local user on wikis that is not member of

STEPS TO REPRODUCE

1. Login as Admin
2. Create a subwiki (e.g. S1)
3. Create a local user on it (e.g. U1)
4. Create another subwiki (e.g. S2)
5. Try to login with the user (U1) on the second subwiki (S2)
6. Try to login with the user (U1) on Main wiki

EXPECTED RESULTS

On the Main Wiki, as well as on the subwiki, the error message is 'Error: Invalid credentials'.

ACTUAL RESULTS

On Main Wiki the error message is 'Error: Invalid credentials' while on the subwiki (S2) the error message is: 'Error: Internal error'.

The issue could not be reproduced on XWiki 11.4 and started failing on 11.5