Timeline Frame animation keeps randomly creating new layers whenever I'm drawing

[MrTristan]

While I'm drawing in Timeline view, Photoshop will randomly create new layers as I brush, sometimes directly above or below my current layer and sometimes even randomly somewhere else in the layer order. It's extremely annoying as I have to find and merge layers everytime I realise I cant erase something. Often there's up to 4 or 5+ new layers created without me realising.
I sketch quite quickly using the shortcuts [ and ] to resize my brush and ` to switch back and forth from eraser mode but I can't tell if this is triggering something.

I have found if I switch off 'create new layer when brushing' in the preferences, while drawing I'll get the warning dialogue: "could not rasterize because the pixel data for this layer is not directly editable" which makes me think Photoshop is recognising my regular layer as a smart object for some reason, even though it's not one (And then recognising the new layer it's created as a smart object too, and so creating more layers again).

If anyone knows what's going on and how I can fix this, that would be amazing. I've been tearing my hair out over it.

Currently using version PS CC 25.3.1 - recently updated from one of the previous version hoping it would fix the issue. It hasn't

[MrTristan]

EDIT:
I'm also noticing now that when the dialogue  "could not rasterize because the pixel data for this layer is not directly editable" pops up and I close it, the animation playback begins. I'm now wondering if this is connected to the SPACEBAR shortcut (I also have this shortcut programmed into my wacom pen) which I use for panning around the page?