Interestingly, if you think about it, this is pretty much equivalent to what Bitwarden is doing. You trust the (open source) client to not leak your passwords a

Interestingly, if you think about it, this is pretty much equivalent to what Bitwarden is doing. You trust the (open source) client to not leak your passwords and to encrypt them properly, and then you use an online service to sync an encrypted blob. A "custom" sync solution is less prone to a targeted attack due to the obscurity, but otherwise is largely equivalent to using Bitwarden (or any other provider with an open-source client and encrypted vault sync).