However I can see when any IPv6 begins with 2a02:12xx:: then it's Swisscom (biggest swiss ISP). But I can't remember any of their hundreds of IPv4 prefixes.
ExtensibleMarkupLanguageHypertextTransferProtocolRequest
https://m.xkcd.com/583/
https://ittavern.com/troubleshooting-asking-the-right-questions/
However I can see when any IPv6 begins with 2a02:12xx:: then it's Swisscom (biggest swiss ISP). But I can't remember any of their hundreds of IPv4 prefixes.