I added the liquid because it was a little below the mines and I suggested that it could be the reason for the under-heating of the fluid, it does not decrease because it has been several months since topping up.
I found only one kalamitka on a rigid hose that goes into the engine block and is connected to the reservoir, but analogously, since the kalamitka is lower than the reservoir and from this point the hose goes up, it should spontaneously vent, unless I'm wrong. I have not found any other vent type valve but I got information that in this car there is probably an electric heater, I don't know if it seems to me that it can be switched on at max temperature settings, for example? maybe the fuse was broken or the trail relay was hit? because nothing else comes to my mind since the thermostat is ok.
Added after 2 [hours] 27 [minutes]:
after unscrewing the vent, the fluid showed up immediately, so there is no air in it, but I don't know if I can bleed anywhere else on the hoses that enter the partition wall, I haven't found any vent.