As something to compare to, I picked a random repository from what GitHub Explore showed, clicked on the first that looked like a desktop application (https://github.com/siyuan-note/siyuan/releases/tag/v3.5.4), and their Windows binary is currently 166MB for a "privacy-first, self-hosted, fully open source personal knowledge management software".

I'd claim 80MB for an entire game engine + editor for said engine is very good.

That is actually pretty amazing for a game engine. I'm not a game dev and I've only ever made some tiny games in Unity back in college but this makes me want to install Godot and try making games again.

What is to note here, this is without export templates, these are ~800MB extra (200 per platform, but it seems like you can download only all at once nowadays).

Engines like Unity and UE include those in the primary download already.