God I hate those no-contact temperature sensors - people use them on literally every surface without realizing there's something called thermal emissivity - different surfaces reflect and radiate heat differently. A glass or metal surface will reflect heat much differently from wood or drywall surfaces.

These cheap no-contact temp sensors usually are set to measure the heat from surfaces found in home construction - drywall, wood, painted surfaces, etc. Some of the nicer ones can have adjustable emissivity but most people never tinker with that setting.

Now if you're using a nice FLiR thermal camera, you absolutely need to tinker with emissivity to get a good image.

Given the fact that the display on this temp sensor does not display the emissivity setting, I'd assume it's fixed - and not set to accurately read the temperature of that metal surface.