A FUT Founder is supposed to represent someone who has played FIFA Ultimate team in the first few months of its release back in FIFA 09.
In FIFA 22 all Division Rivals opponents are shown to be a FUT Founder in an attempt by EA Sports to tackle toxicity.
You can see when your opponent's clubs were created in FUT Champions and it will be EST. Month 20**
For example my club was created in September 2016 so if you played me in FUT Champions at the end of the game it would show EST. Sep 2016