(Background Information: I was playing around in a creative world the other day and I was trying to make a Raid farm. I had captured a villager in a 1x3 hole in the sky made with slabs. Once the raid began, I tried to place a few more and it would rapidly place blocks. I tried it on the ground and it worked normally. Whenever I'd try to build next to the villager, it would happen. I had to move the villager to another corner to get it to stop.)

There's something about the hitbox that makes placing blocks wacky and place way too many. Anywhere outside the hitbox is fine, as far as I've tested. Here's a video showing it happening.
sorry for the YouTube link, but the file was too big for the website haha.

https://youtu.be/hgXvKZDIPiY