That issue with the probes is likely due to cleaning them. Every probe I have, has a terrible seal where the wire passes through into the metal. I think the all do because you can’t get a good crimp there without messing up the wire. And for whatever reason they cheap out in that spot with a Teflon sleeve (I think) around the wire in the crimp area.
End result is you get water down in there eventually no matter how well you take care of them, which messes up the connection inside and makes the temp go all over.
I specifically clean mine in such a way so that water doesn’t get inside and they still break after awhile.
If they aren’t that bad off I sometimes use them to measure temp inside the smoker, but you have to test them out and mark them with how far off they are. So really just better to get new ones so you don’t make a mistake.