Ah, Oldrim, should have specified that too. I'll try just disabling that mesh and see if I can trigger the issue again.
EDIT: As far as I can tell, this deformation only occurs in Whiterun, only in the presence of other mods (currently trying to figure out which one), and occurs randomly on cell transition.
Also, if you continue to enter/exit the cell after mesh has already started to deform, bad things happen.
https://i.imgur.com/5682Hlv.jpg*replaced image with link because it's too big for my tastes
EDIT 2: My previous observation that this occurs due to another mod was incorrect, my sample size was simply too small. With nothing but ENB, SKSE, and the particle patch (everything else disabled within MO), the deformation of this mesh still occurs - but still only in Whiterun, which is the most baffling bit. Going anywhere else with that particular mesh and performing the same procedure (repeatedly transitioning in/out of a nearby cell) results in no issues.
Furthermore, renaming or removing the fxfirewithembers01_cheap.nif does seem to fix the issue, but also results in the particle patch obviously not applying to these fires.