Removing the folder didn’t solve my issue, but I probably found what causes it: in the RAATServer logs, the machine ID of my remote is the same as the machine ID of my core. (Probably because I initially set up the new Mac based on a backup of the old one.)
I found another thread about a similar issue (see Problem Running Roon Remote on MacBook Pro). They didn’t find an answer that didn’t require a complete OS re-install though.
So the challenge is changing the machine ID without having to re-install the underlying OS, possibly by changing some variables in the OS. Is this possible? It would be helpful to know exactly how the machine_id is determined?