Is there something about your Chrome and FF configurations that have them using different DNS sources? For example is one doing DoH and the other using the system resolver? Different DNS servers may be geographically diverse, getting different GLB answers, and sending you to different WhatsApp servers?
Just a thought.
When I go to https://www.whatsapp.com/ I see the page in Latvian - but
only on FF.
When using Chrome I see the page in English.
So who is doing bad geolocation? FF or Whatsapp?
Thanks,
Hank