I don't think you understand what filler is...
It is an action-comedy and slice-of-life, (that focuses on three characters). I think the way Endo-sensei does things helps give him a break and helps him creatively (especially since there was a period when he was struggling creatively, that why SpyxFamily was born).
Also, fillers mean episodes or story arcs that are not part of the source material, such as a manga or light novel. We have a chapter called short missions, and the last one was 17. That offers a look into the characters' lives outside of the main plot and it helps expand the world.
You can be disappointed in the way things are processed. That just how Endo-sensei wants to bulid his story
I love this story sm but the recent chapters have been all fillerrrrrr i want the story to progress