certificate for tableau desktop are not valid anymore but users can startup the software

While opening or starting up the Tableau Desktop software we got an error saying "certificates explicitly revoked by its user" PFA(tableau desktop old version 2020.1.2.png) for more info.

So recently we have upgraded the desktop software to 2020.3 then after tableau desktop can startup but the certificates were still not valid PFA (tableau desktop.PNG),

I understand the desktop software was unable to startup on old version because the certificates are not valid.

But what I don't understand is why the software was able to startup even after the certificates are still not valid.

Here I wanted to know

Q1)what exactly went wrong ?

Q2)how exactly the software works?