Aegis but it just works on Android. If possible use a 2FA app that is open source and doesnt't have internet connection.

I use vaultwarden/bitwarden

Not sure about syncing, but I use Aegis on Android and it works well

I use a keepass database with KeePassium (strongbox looks great too).

I keep the database in the cloud but it’s unlocked by a local keyfile on each device. So if it’s compromised they would need the keyfile.

KeePassium keeps a local copy and backups if you lose connection.

I you are willing to self host, 2FAuth is pretty good.

I use Pass (https://apps.apple.com/il/app/pass-password-store/id1205820573) which is an iOS version of pass (the command line password manager) that also supports pass’s 2FA extension.

2FAS or a KeePass vault kept in sync on both, which can store TOTP private keys and display them when needed.

I use KeePassXC and you can sync it with Syncthing. On iOS there are alternatives which a compatible with Syncthing and the KeePassXC database, it works very cool once you figure out how to do it and you also got all your passports synced too with it.

keepassxc for desktop and for Android: FreeOTP+ (the plus is important)

I use 1Password for mine.