I've not heard/read this before, but I use Mullvad and my anecdotal experience confirms this. I get blocked or put into a captcha trap quite frequently. I assumed this would be an issue for any/all well-known VPN IPs. Are you saying that it's not? Do you have any alternative recommendations?
It looks like this might be the beginning of a Cloudflare style service that lays down the backbone for other VPNs to hop onto.
Mixed feelings.