I know the jam even states:

If you are new to Godot, we suggest using version 3.5.2 for a stable experience.

but was wondering if anyone has recent experience with using the latest Godot 4.1 with HTML5 export - is this better than the early Godot4 struggles? Or is it better to still use Godot 3.5 for jams with HTML5 export?
Thanks!

I don't know about early GD4, but it is still buggy. I just opened an issue on GitHub, because I ahd invisible walls in my game that I didn't code.

I'm still gonna use 4.1.3. Masochist life style, I guess. ;)

A couple of jams ago, I exported to html using godot 4. I didn't have any problems with it, and everything worked well. This is the tutorial I followed: 

Note: 

1. my game was entirely 2d

2. I only used basic animations

3. Nothing about my code was particularly resource intensive

Your mileage may very, but it worked for me. 

You can export HTML from Godot 4 but only the standard version. It wont work from the .net version.