I am working with QB Enterprise 2021 desktop version.

This is still an issue.  I am experiencing this same problem today (11/30/22).  After sending out invoices 2 days ago i received a message from one of the customers who is trying to pay his invoice, but is getting the same error message on his end.  What is weird is that i just sent out a "Payment Link" to another customer and it works perfectly fine so I cannot see how this is a "browser issue".  I just need a consisently reliable way for my customers to pay their bills online (so that we can pay ours :-)).  When I click the "contact us" link it just takes me to another article, which is how i eventally ended up here.  For anyone that has had a fix with this that can share what they did to resolve I would appreciate it.