Just putting my two cents worth in: same issue here. NFCU app worked fine the last time I tried (months ago). I updated today when I tried accessing it again and it freezes on the blue screen with the NFCU logo. I've tried with Exploit Protection on and off. Rebooted, uninstalled, re-installed, force-stopped, cleared cache and storage. Didn't help. I'll look for that native code debugging toggle.
One other data point: When I first opened it, I had the old version. It appeared to be working there. But, I was prompted to update and did so before trying anything else. After the update, it went nowhere but stick at the blue logo screen.
EDIT: it turns out, Native Code Debugging was one already. Also, the app doesn't crash on mine. It just stays sitting there. However, I've swiped away from it and after a while, the phone stops working (taps don't register). I've had to reboot from that.
EDIT 2: Sorry, forgot to put my phone info: Google Pixel 6 on T-Mobile, GrapheneOS 2023041100.