PureVPN fixed their leak already. https://www.wilderssecurity.com/threads/detecting-vpn-leaks.383636/page-6#post-2739574
OK, so this is one key reason why we don't want VPN services in browsers. These were bugs in browser extensions!
VPNmentor praises HSS for their quick response, but given how elementary & silly the vuln is, I won't. It's not a bug which can occur even in a code written by experts. I, less than so called script kiddy, can understand the bug and it's really ridiculous, reflecting how much they care about user privacy. These 3 have already been in my VPN black list, but it reassured my listing.