Access rights not recognized since 4.2.3

Since version 4.2.3 I'm having issues pulling, pushing, fetching, etc. and getting various errors such as:

ERROR: Repository not found.
fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.

or on another machine, that is configured similarily, I get the following errors (multiple times):

git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.

However, when I `git pull`, `git push` or `git fetch` from the command line, everything works as expected. Also everything works as expected with version 4.2.2 and prior.

I've tested all of the following versions and they do not work for me: 4.2.3, 4.2.4, 4.2.5, 4.2.6 and 4.2.7

I should also mention that my machines are configured in a way which supports multiple GitHub users as described in the following guide: https://blog.gitguardian.com/8-easy-steps-to-set-up-multiple-git-accounts/amp/

If you need further information, just let me know.

I currently have no other option than to either use version 4.2.2 (even though according to the changelog some security vulnerabilities have been fixed since then) or to use a different client.

Could you please take a look at this issue? Thanks!