I don't think this problem has anything to do with our recommendation to install Certbot through snap on Debian now. In fact, doing this would likely get your Certbot installation working properly again with automated renewal, but if apt/dpkg are still in a failure state, I don't think it'd help to solve that problem.
I unfortunately don't know enough about this to really offer guidance here, however, I sent a link to this thread to Certbot's Debian package maintainer and hopefully they are able to make a suggestion here.