I didn't realise that Opera was now Chinese or that it's based on Chrome. I checked and, sure enough, it was sold to a Chinese consortium in 2016. AFAICT, the VPN is provided by SurfEasy (not Google). Doing "whois surfeasy.com" suggests that SurfEasy is owned by Symantec (who IIRC also do Norton security products). However, I suppose it's vaguely possible that Google could have embedded key logging etc. in the version of Chrome upon which Opera is based and there's still the issue that (I assume) Opera's servers are at the end of the VPN tunnel and so have access to everything in unencrypted form.[...]
My preferred browser is and has been Opera, for over a decade. But to fuel your paranoia it is nowadays based on Chrome, owned by a Chinese consortium, and the built-in VPN service is provided by Google.