Proton has a free new authenticator apps, which is available cross-platform with end-to-end encryption protection for data.

Bitwarden Authenticator is a standalone app that serves TOTP for free. You can continue using the paid feature, switch to the free one, or use both, as the apps are independent.

Bitwarden has developed a standalone authenticator app. Until now, time-based one-time passwords were only available as an additional function for subscribers.