Apple ID third-party sign in not working

Apple ID third-party sign in doesn't work on Opera GX.

Here's what happens: I try signing into something with my Apple ID. It asks for my username and it autofills it. Then it asks for passkey/password and I type in my password because I don't have any devices capable of running iOS 17. After hitting submit, one of two things happens:

1. The screen shows the site I'm trying to sign into (GroupMe, LinkedIn, etc.) asking if I want to trust the site with my account or something, but it disappears after a fraction of a second meaning I am effectively "softlocked" from signing in and have to try again. It does not reappear and trying again does not work.
2. The username/password menu disappears like normal, but the screen becomes completely blank, with no clickable entities.

This problem has persisted across the last few months. I need a solution as soon as possible because it is interfering with my ability to sign up for a job. I can't do anything without a job.