I imagine you keep your password manager unlocked, or as not requiring 2FA on trusted devices then? Re entering 2FA each session is annoying

You still have the treat of viruses or similar. If someone gets access on your device while the password manager is unlocked (ex: some trojan on your computer), you’re completely cooked. If anything it makes it worse than not having 2FA at all.

If you can access your password manager without using 2FA on your phone and have the built in phone biometrics to open it like phone pin, finger or face, someone stealing your phone can do some damage. (Well, the same stands for a regular 2FA app, but meh, I just don’t see an improvement)