Since around July, when using a sleeping bag, which is added with Comforts, a spawn point that should not be set has been set. This means that if I die after using a sleeping bag, I will respawn at world spawn point instead of my bed. This issue is also reported here.
This also happened with night bags from Sleep Tight, so this is not the issue caused by themselves. After a hour of test, I found what causing this issue actually is this mod, Cold Sweat.

So, here's the crux of the issue:

• Beds are supposed to set your spawnpoint even if you can't sleep in them. Forge has it set up so that if you cancel sleeping in a bed with your own custom message (i.e. "it is freezing outside"), it also cancels setting the player's spawnpoint, so I have to set it manually
• I can't check which blocks are supposed to set your spawnpoint, because there's actually no common thread I can find between Vanilla beds, Comforts, and Sleep Tight. All of them reimplement the same mechanic in their own way.

This means I have to choose between being consistent with Vanilla behavior or fixing the issue with these mods; but I recognize that this completely breaks these sleeping bag mods, while removing it would be a minor inconvenience for Vanilla beds. I will continue looking, but the simple solution is to just not manually set the player's spawnpoint.

To update on this issue, I've decided to not set the player's spawn manually, which means you won't be able to set your spawnpoint at a bed if you're freezing or overheating, but it fixes this issue