I have assemblies with multiple steps and exploded views. I consistently collapse the exploded views as I move through the document from step to step, and before I save & close.
Since 2021 SP1.0, when I re-open a document, or toggle from the drawing back to the assembly I will find exploded views active in their exploded state. The assembly step is closed (greyed out) but the explode step is active (black text) and the parts for that step are exploded.
Never had this problem before.