I just migrated from KeePass myself, so I can answer this.
- All custom fields will be migrated
- Auto-type isn’t supported
- I never used it personally, so I don’t know if it will copy the sequence to a custom field or not
- TOTP keys are only migrated as custom fields
- You’ll need to manually copy the key from the custom field to the TOTP field
- I tested with both KeeOTP and TrayTOTP
- Attachments did not migrate at all
- Expiration dates did not migrate at all
- Expired entries DID migrate, however
- No support for custom icons
- Folders don’t have icons
- Bitwarden doesn’t have a history feature, so that won’t migrate
- The “Exposed Passwords” option in the “Tools” menu will tell you which accounts are using known leaked passwords, so there’s something
- The “Data Breach Report” is pretty basic, manual search for a single email or username
I also want to note that attachments and TOTP are premium features. I didn’t buy a subscription until after I imported everything from KeePass, so it’s possible the attachments could migrate if you get premium beforehand.