Double-check that your APT sources are exactly what you expect them to be.
Clean your APT cache. Then update it.
Try to fix broken packages again with apt install.
If the problem persists, look at every single package mentioned in the error. Go to the Debian packages website and look up what the current version for your release is. If there are any mismatches, try to resolve them by uninstalling these packages until apt install completes without error again. Make sure to reinstall the right version of your packages again.
Given your other comments about manipulating post installation scripts for some time, if the above doesn’t work for you, consider backing up your data and reinstalling a fresh setup.