I'm running into an issue where when I get hit by an acid attack, my players controls invert and my player speed is modified, sometimes to be slower, sometimes much faster. It fades away once the acid effect wears off.

I did testing and it looks like even without your mod installed, if I spawn a spitter above Rare quality using /editor, its acid attack affects movement in this way, so I'm guessing its a default scaling in Factorio related to quality on spitter acid attacks. Wondering if you can override the attack behavior to avoid this or maybe add a mod option to disable acid slowing effect since its bugged with certain quality spitters.

Edit: After more testing, it actually looks like this is cause by Combat Mechanics overhaul and this mod together, just FYI if anyone else reports.

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Is there any plans to fix this?

There is nothing broken to fix. Quality does not scale movement reduction effects of acid, only it's duration.

Did some testing and I was able to replicate it using only the Combat Mechanics Overhaul mod, and cannot get it to replicate with just vanilla+SA. So I submitted a bug report to mod discord.