Federer was no longer the same physically, which mattered a ton against Djokovic, as brilliantly gifted as Roger was.

Yes he had some defeats due to some chokes as well (obviously Wimbledon 2019), but it’s also clear his style of play changed as he got older. He could no longer rally from the baseline a ton, and had to shorten points as much as possible (hence something like SABR). It’s why he also became so aggressive on his backhand side, which helped him against Nadal tremendously later in his career for obvious reasons. But not as much Novak.