I saw GDPR related blockage like literally twice in a few years and I connect from EU IP almost all the time

Overload of captcha is not about GDPR...

but the issue is strange. @benhurmarcel I would check if there is somebody or some company nearby abusing stuff and you got under the hammer. Maybe unscrupulous VPN company. Using a good VPN can in fact make things better (but will cost money) or if you have a place to put your own all the better. otherwise check if you can change your IP with provider or change providers or move I guess...

not to excuse CF racket but as this thread shows the data hungry artificial stupidity leaves no choice to some sites

Does it work only based on the IP?

I also tried from a mobile 4G connection, it’s the same.

This may be too paranoid, but if your mobile IP is persistent and phone was compromised and is serving as a proxy for bots then it could explain why your IP fell out of favor

You don't get your own external IP with the phone, it's shared, like NAT.

Depends on provider/plan

I get a different IPv4 and IPv6 address every time I toggle airplane mode on and off.

Externally routable IPv4, or just a different between-a-cgnat address?

Externally routable IPv4 as seen by whatismyip.com.

I found it's best to use VPSes from young and little known hosting companies, as their IP is not yet on the blacklists.

One of the affected websites is a local cafe in the EU. It doesn’t make any sense to block EU IPs.