On public WiFi I just vpn into my home network. The issue with public WiFi is that it can be sniffed by anyone in range since there is generally no encryption.
Although pretty much everything we do is over tls these days, and DoH helps protect against even dns sniffing. There’s still at least some risk to working in the clear over a public WiFi network. At least in information gathering, what bank you use, etc.
But, there’s no real benefit in using a paid vpn over one you own unless you’re downloading illegal content, want to watch another Netflix region, or are in a country with heavy Internet monitoring/filtering.
Possibly the domain is visible with a traffic monitoring tool. Everything else is between you and the bank via HTTPS. Having said that, whatever is not over https is visible to whoever sits on the same network as yourself.