Okay, so I tested this mod in FU. Everything seems to be working as intended, so verdict: mod is compatible with FU!
I only tested on vanilla planets though with level III EPPs of cold, heat, and radiation, along with the Breathing EPP. I also took Anter's comment into account when testing, so I also saved and quit and then re-logged into the worlds each time.

This mod does seem a bit redundant when used with FU though, since I personally have never encountered this issue and I play with FU. I was actually brought here when making a modpack for someone :) but it never hurts to have extra protection when you are concerned.

This bug also happens with airless environments, right?

Never happened to me but Im glad its fixed

I always wondered why this error happened, in my case it is very common that I have to save game being in the depths of a planet foraging minerals.

Sometimes it has happened to me that being with the minimum health (caused by this error), I have been killed by enemies nearby, losing 1 hour of farmeo (sometimes it costs to find again where you died if you moved a lot).

Thanks for this.

I was wondering if it would be possible to include your FIX in a translation mod that I have in the workshop, it already has some fixes incorporated, and it would be interesting to include this one, if you give me permission, of course, your credits would go in the acknowledgements section of the patch notes.

it happens even with persistent stat groups, which Betabound uses ;-;

Definitely happens in Betabound... <_>'

Huh, so many years in game and never noticed the problem, anyway, thanks!

ohhhh, ok that makes more sense now. thank you for the info

I don't think I explained it well enough in the description, but the bug specifically happens when you save & quit while on a planet/location that has any of the 4 environmental hazards.

When you join in again you usually get a S.A.I.L warning even though you're already wearing the proper EPP and on radioactive planets you briefly suffer from the 10% health multiplier debuff.

this can happen?
well im not takin my chances