MFA using an SMS is not secure.
If people reliably made good passwords and never reused them, we probably wouldn't need MFA as much.
Unfortunately, we live in a society. Bitwarden will remember your TOTP codes for you across any device you login from. It will even copy the code to you paste buffer during a login.
I enable MFA everywhere i can, even for stupid stuff. Its just not an inconvenience using bitwarden.