If your concerned then please do approach a Samsung Experience Store or Samsung Service Centre who can take a look or go to the source who supplied your phone @andy198009
I wish you all the best with this.
Current Phone > Samsung Z Fold³ 5G.
If you've enabled Adaptive brightness on your phone I'd suggest switching this off when video calling, as the screen brightness tends to increase during video calls, which can cause the battery to heat up more than usual. To disable this feature, head into Settings > Display > Disable Adaptive brightness.