Migration protocols require the keys to be representable (at some point) as clear text.
And password managers like BitWarden only allow encrypted export, but the encryption key is specified by the user. So you can trivially decrypt the exported data if you want.
I don't have a dog in this race. Just showing where the other understandings come from. Your logic might lead one to conclude that migration would not then generally be available.
And password managers like BitWarden only allow encrypted export, but the encryption key is specified by the user. So you can trivially decrypt the exported data if you want.