Like a few high-profile projects that have also reconsidered choosing Godot 4, I require something more performant and stable/compatible than Godot 4.x. The "improved" engine only manages a fraction of even GDSim's performance. Features formerly present in Godot 3 regressed to being incomplete and still aren't restored.
However, Defold's 3D physics support proved too limiting.
I spent enough time away from Godot to cool off on how badly it burned me, enough to try again in Godot 3. The in-progress results in Godot 4 were so dismal -- after months of learning how to work around breaking changes & new bugs -- it was upsetting.
I'm not happy how so much time was blown on Godot 4, but the silver lining is, rewriting the project multiple times has made for better code.