There have been reports and it is also observed that MediaTek processors heat up more than the Snapdragon processors.
It depends on the build-quality and build-technique of the chipset.
Hence, the safer choice would be to buy devices with Snapdragon processors.
The built materials used for making the Xiaomi Redmi Note 8 Pro are Plastic and Glass.
The Plastic gives the phone its rigidity whereas the Glass gives the phone a classy look.
Have a look-
Check Full Device Specifications Xiaomi Redmi note 8 Pro