I see, it is reproducible by just performing inputs during the save in general. I just happened to have only noticed it during attempts to place a machine in the world.

So this is a problem in Wayland, not Factorio. Especially seeing how saves tend to take longer now that there are multiple ...

The game crashes if a modification is made to the world (by placing a machine for instance) while the saving progress bar dialogue is visible.

What did you do?
I was able to reproduce this pretty consistently with some effort. It seems to be independent of a specific save.

I created a new save ...