how can I transfer time machine backups to a new external drive?

I don't know, yet, man. That error is new to me.

One thing I saw in a quick internet search is that the new drive must be formatted with matching formats as the old one (like macOS Extentended Journaled Encrypted, etc).

Not sure this still works since Apple archived it, but I see you're in High Sierra, so maybe that'll do Transfer Time Machine backups from one backup disk to another - Apple Support

You can also simply transfer the .backupbundle file to another drive and then set that one as TM drive.

Click on this -->

Transfer Time Machine backups from one backup disk to another - Apple Support

Nice!

Yeah, sure, man.