I too need to disable my VPN (Mullvad) in order to use Kagi. It's a somewhat uncommon event, but it is a problem for a number of reasons and is a pretty big degradation in quality-of-life.
I have a hard time seeing how this is a problem with the VPN provider as all other sites work perfectly fine when this occurs, which leads me to believe that some - by the Kagi servers - assumed bad actor has been using the same VPN server as me.
Wouldn't it be a reasonable request to tie IPs used by valid account to a whitelist? Or, if the bad actor is a valid account, still let other well-behaved subscribers use the IP?