Hello,
I'm on PC running 3.5.51.
I'm using the outline window, but each time I'm launching Spine, if I zoom out (or zoom in) inside the outline window just one time with the mouse wheel, it zooms out several times as if I were using the mouse wheel several times.
Here's a gif.
Loading Image
I just noticed that it might happen only when I can see 100% of my "scene" in the outline window. If it's already zoomed in, the bug doesn't show.
But it's happening just once per file. After that, this little bug is going away.