maybe sudden death?

for starters i have a pretty big tank with lots of food verities and proper substrate, I did just learn i have the wrong moss and today is tank matince day so i will be taking it all out, they do have both fresh and salt water (i use the seachem prime from south of the ocean and my salt water is made with instant ocean). I also just replaced there light(hygger aquarium light 28in) and it’s on a 24 hour timer starting at 7 am ending at 7pm. I do keep there tank humid but my temp and humidity readers need replaced because the stopped reading correctly. I do watch it more because of that and i am around this tank a good 24 hours out of the day. I do not use candles or any sented things and I use cleaners I have made that are more gentle (still efficient AND NEVER FOR OR NEAR THE TANK) me and my mom are asthmatics and have problems with some cleaners if you needed any reasoning for that. I do have a heat mat on the back of my tank and a heater in the room because it is winter and it’s freezing in here. I also did just make a post about a surface molter but that is handled and i really appreciate all the help.

now to the crab i seen him yesterday moving around and before that he was really active in the nights not really in the day (he’s super shy). however I checked on him because He hadn’t moved since i had went to bed at like 5 am and he is not moving anything. i did try to put a flower in his claw to see if it would move but it did not. I think i may have seen him move but i may just be running on fumes rn. i will include pictures of my tank and i do also have two painted shelled crabs i know its bad one is in an iso box (surface molter) and the other has a clear coat on her shell that i have not seen chipped yet and these guys are getting there own little baskets of shells to pick from when they arive.