We have had issues with 2 Galaxy S21 screens being hot to the touch. We purchased through Verizon online. For the most part that was a very hard and long process because order got hung up. Then reported screen hot, replaced one phone already, and still hot. I went to local corporate store which is 1-1/2 hours from my house. Spent 2 hours at the store to no avail. So 5 hours wasted, to be told to come home an call customer service. Spent almost 3 hours on phone, and no resolution. Very frustrated about lack of service, and customer care. We currently have 10 lines on account, and have been customer for several years. Definitely have to wonder what the next step is.
I would be just as upset and frustrated over this entire experience, Lost_in_Virginia. Please know that we truly value you as such a loyal customer, and we want to continue a healthy and happy relationship for many more years to come.
How long ago did you purchase your Galaxy s21 devices? Do both have the same issues? Have you contacted Samsung at all?
I suggest you submit an error report to Samsung Members app when it occurs again or try reproducing by doing as 'exact' as what you(or the user) did at the time of heating up.
BUT, first... do you know roughly what the temperature was? It is considered overheating if it reaches over 50C or ~120F degrees, or sudden overheating in very short time when the usage was minimal.
If the phone was in a hot environment (outside on a sunny day when it's >100F like Texas) or was using the camera or playing games for some time... it's a bit hard to determine that the phone was behaving abnormally as those do result in warming up the device.
One additional thing you can do is to take it to UBreakIFix and ask to check the battery, see if it's behaving normally or has any sort of issues/deformities
Your safety is always our priority! To confirm, do you get any temperature warning messages? Is the screen getting hot while charging or when the phone is in use?