It might take a couple of days (since it is random), but it looks completely different/random on each site it happens on. Therefore I don't see it being necessary to post a screenshot.
The page just does not load correctly (some of it can load, and other parts do not load). Sometimes in YouTube it does not even load the comments until I disable Avast.
One time in YouTube it even just said "No Internet" or something like that, and I also had to disable Avast to load the page correctly (when just searching for videos).
When the error occurs on Reddit, it only loads a couple of posts and then when scrolling down it is impossible to load more posts until I disable Avast.
So, in short, each page looks different when it does not load. There is usually not any error code or stuff like that, only that the pages themselves are not fully loaded until I disable Avast and refresh the page (just refreshing without disabling Avast does not fix anything).
Though sometimes the page does not load at all, it just keeps acting like it will sometime in the future load (like an infinite loading), which is also corrected by disabling Avast.
In the start when this started to happen, I had to go into my other computer to work, since this computer (which use Avast) could simply not load the page I required (this was before I knew it had to do with Avast).