Yesterday I migrated an account from bitwarden.com to bitwarden.eu.
I did it with a password encrypted json export and import (from both web vaults).
I was surprised to find out [*] that items on my destination vault had the password history from the source vault.
OTOH, metadata information (like item creation and modification dates) was lost.
[*] : contrary to what that How to Create and Store a Backup of Your Bitwarden Vault guide says said.