Not only was Broly first introduced in the Dragon Ball Super movie, but Gogeta made his canon debut as well. Much like Goten and Trunks, Goku and Vegeta were unable to successfully perform the fusion ...
Broly and Jiren both exceeded the strength that Goku and Vegeta had in their Super Saiyan Blue forms. Broly's potential power may have allowed him to overpower Goku even in Ultra Instinct form.