To the contrary, Game of Thrones was too short. The books were just so long and detailed that even 8 seasons did it no justice. I think the mistake was making the show before the books were finished being written and spending so much time on the first couple books so that the later seasons were just skimming through the major plot points from the books.
Breaking Bad definitely went off the rails in the final seasons but I felt they were a quality show until the end; if anything the original tone was kinda goofy for how serious and dramatic it ended up being.
GoT however has gotten much worse the closer they got to running out of source material. The last season I watched had incredibly stilted dialogue and relationships (Jon going rambo all the way to the north with no plan and then falling instantly in lust with Danny) and the pacing was hyperspeed compared to the previous seasons. If anything it feels like they really want to end it but have run out of room so they are just rushing it.
This stuff exists on a spectrum. The near end in my opinion are shows like GoT and Breaking Bad have long narratives to tell and imo they use the time well.
Further away are shows like Archer which were amazing when they came out but tend to drag on without having a significant story to tell.
The far far end is exemplified best by animes like Dragonball or Hunter x Hunter which go ON AND ON AND ON and somehow never seem to go anywhere.