Luckily, I was concerned about some changes in LastPass a few years ago and moved to 1Password, then to Bitwarden. I had helped set up some family members with LastPass and I encouraged them to do the same -- most did.
Unfortunately, some of them forgot to delete their LastPass accounts after importing their data.
This morning I wrote a script that takes a user's exported LastPass data (comes in csv format) and a terminal logged into their Bitwarden account (with Bitwarden CLI installed) and tries to match on existing Bitwarden data that could have been compromised via LastPass.
Hopefully this is helpful for some of you. I'm a hobbyist, so don't expect professional code!
