I’m not a business guy and I don’t know how trademarks work as well as others may. I do know that when a company like WWE abandons a trademark it usually means they have cut ties with a performer.
According to a report WWE has not renewed Brock Lesnar’s trademarks. Brock last wrestled at Wrestlemania 36 where he lost to Drew McIntyre and has not been seen on their programming since. Brock’s contract expired and according to the report did not give his written consent for WWE to continue to trademark his name.
Brock reportedly makes a lot of money off of merchandise so letting that go is a clear sign he is done with the company at least for the immediate future. As of right now all of his merchandise has been pulled from the WWE shop.