Faster tempchange on ITC-308-WIFI

I have a problem with the thermostat. It takes to long to notice when it’s hit the target temp. Both up and down.
I have a warming band connected to the hot outlet and it’s placed on a stainless steel vessel with fermenting beer inside. The temp while fermenting is very important and when it differs over 1,5 degrees Celsius it can affect the finished product.
This wasn’t a problem when I bought the product. Do you have a suggestion of what I can do to fix it?

Please put the probe in different positions and test it. Will its reading still change slowly? Will it deviate by more than 1.5C?
If yes, please provide your order information and ITC-308 problem video to email for after-sales service.