kcorny I feel like the term "fillers" have been misused and thrown about too often and very unfairly. At some point, anything that the readers don't want to read or find boring gets labeled "fillers."
Take Forty Millenniums of Cultivation, for example. Li Yao boards a train to get to his university, and something happens there that has a significant impact on the way he views cultivation, as well as expresses the general world-view of cultivators. But you have a ton of readers jumping in and complaining that the entire arc was a "filler" despite the event being life-changing, important and relevant for Li Yao and the story, all because...they just want him to get to the university and start, I dunno, kicking ass.
Now, I can understand if you call the irrelevant chapters of Battle Frenzy where the author goes off to talk about the Empire and politics, which have absolutely nothing to do with Wang Zhong (and very tangential to the main plot) "fillers". Those sometimes come across as massive info dumps that deviate from the current arc. However, you have annoying readers who complain about every single slice-of-life scene, when Wang Zhong goes out with Scarlet or when he interacts with his schoolmates/society members as "fillers" just because they want to skip everything and go straight to the action. Like, seriously? Stories are not 100% action, the characters don't spend 100% of the time doing nothing but train and fight. Character developments, exploring their relationships with other characters, seeing what they normally do in school outside of training/fighting is also part of the story and the world. But no, if they aren't fighting, it's automatically classified as "filler" and readers whine about it.
I can understand complaints where the writer goes off on massive info dumps on things that have absolutely nothing to do with the story as fillers. I can understand word padding or whatever as fillers. But some of the accusations readers make of certain chapters being "fillers" are just inane. Just because you don't want to read them or you find them boring doesn't mean they are irrelevant or "fillers." It's a story, not a collection of action scenes incoherently stitched together. Protagonists have their own lives too, they don't just fight 24/7.