Hi how much is Maximum

I don't believe there's a maximum based on a google search of past threads.
https://forums.d2jsp.org/topic.php?t=62686366&f=34

But I do know if you intentionally post an oversized image (i.e. multiple scrolls), then it can constitute for warn %.

I just tested a larger 1920x1080 and it worked for Gallery.

Not sure of the limit but I do believe it's pretty large for gallery, signatures for sure have an outlined limit though.

Staff member or someone who knows for sure might have to chime in here for definite answer.