For them both to be doing the exact same problem leads me to believe either a problem with that particular model or something happened that damaged them, like a surge and they haven't been the same since. I have been using inkbird for a very long time and never had any errors that were the fault of the thermostat. I have never done the wifi ones though. I really don't see the point in a wifi thermostat to check from afar because most of the time any problems are going to come from probe becoming displaced or the thing break all together - which wifi is not going to help alert you to well anyways.
I'd just get two cheapy normal inkbirds without all the bells and whistles ASAP before your snakes get sick from malfunctions and then if you want to try and get some other fancy wifi thing later when you have more money you can.
Maybe so. But without wifi I wouldn't even know there's a problem so it would just sit there. With knowing there's a problem I could rush home as soon as possible or alert soneone else to look after it.