I really think that 'average' is a myth when it comes to chapter length. It depends so much on genre, pacing, and the author's specific style. You'll see 1,500-word chapters in some fast-paced thrillers that just slam from one cliffhanger to the next, but then in a dense historical fiction or epic fantasy, a chapter can easily sprawl to 5,000 words or more as it builds a world.
I used to get hung up on this when I was writing, constantly checking my word count against some imaginary ideal. It made my chapters feel so stilted. Now, I look at the rhythm of the story itself. A chapter should end when it feels right, not when you hit a number. That said, in trad-pub fiction, I've noticed a lot of modern books seem to settle in that 2,000 to 4,000-word range per chapter. It's a digestible chunk for a reading session before bed.
My personal sweet spot as a reader is about 3,000 words. It's long enough to sink into the scene but short enough that I can finish one and feel like I've accomplished something, even on a busy day. I just finished a sci-fi novel where every chapter was a neat 2,500 words, and it made the whole experience feel incredibly streamlined.