That's actually a good example - The early seasons aren't necessarily worse because of the end of the show, but it definitely killed a few spinoff shows HBO was planning, and also killed the Star Wars movie that the showrunners were working on.

Obviously we're still getting House of the Dragon, but if you'd told me before the last season came out that we'd only have 1 spinoff GoT show now, and that it wasn't that big of a deal, I'm not sure I'd have believed you.