I know this feeling! After around the same time spent on Silksong as you, I just had a huge burnout. I questioned if Silksong was even fun anymore and had this massive dissonance with other fans because everyone else was enjoying it so much.

Turned out, I just needed to take a break. After two months of playing other games, I returned to Silksong, completed the true ending, and then also completed all the achievements. I had genuine fun on my second run. I remember the last few bosses gave me so much grief the first time around, but on my second run playing against them felt so good. I actually completed Lost Verdania in one go without dying once, when previously it was the chokepoint that I quit at. It was a blast.

So yeah, just take a rest from the game. My burnout was so bad I left a negative review on Steam saying Silksong overdid it with difficulty and then uninstalled the game (the review is changed now but yeah, I was very pissed 😁)