Might be worth looking into and reporting as a bug. I use wayland and very commonly watch a high quality video on one monitor and whole games on my other just fine.

As someone who works in security, I don’t personally recommend self hosting your password manager unless you’re planning on never opening it up outside your network or you’re willing to be on top of all potential security issues. These are your account credentials we’re talking about. You WANT them safe, and the people paid to make sure they stay secure are likely going to do a better job than you.