Quick Update: I backed up my data and did a factory reset on my phone, which resolved most of the issues. Around 90% of the problems are fixed, though I’m unsure if they might return. For now, the UI feels much smoother.
After the 3.0 update, I noticed several bugs, like a random mouse cursor appearing (similar to using a Bluetooth mouse via OTG). That issue is now resolved. I also found the new app archive feature, which wasn’t available before the factory reset. However, I’m still unable to set wallpapers via the Nothing Gallery app. It works if I enable Google Photos, but that makes Google Photos the default, which is inconvenient.
Network issues are mostly resolved, though occasional inconsistencies remain, which seem to be caused by the operator.
With more storage now, the system feels fluid, but I still need to test it with heavy apps and games. I’ll provide an update after a week. Thanks to everyone for the suggestions—it really helped resolve these issues.