I’m at my parents’ place right now and looked at it. It’s a Roku Express 4K+.
I don’t know what the issue is but I don’t think it’s a bandwidth limitation. I can get a consistent 30 mbps on speed tests even with other users, and when I use the computer it’s via the same Wi-Fi. It may be related to the API for specific apps. Disney+, Paramount Plus, and Apple TV+ look fine. It’s a couple of sports apps with streaming feeds where the quality just drops often. It doesn’t look like a max resolution issue - just that it looks blocky most of the time.