unfortunately the blocking of servers is a perpetual battle that plauges almost any publicly listed proxy (vpns, tor, etc). the only way I have found around it is using lesser known/blocked VPNs or residential proxies. both of which probably have subpar data privacy policies, if they even follow them at all.
althought it likely won't help your captcha troubles, I would like to give a huge +1 to mullvad. have been a happy customer for years. in compsrison to proton as a company they have a much more direct/benifitial effect on the web & furthuring users privacy online in my eyes.