I monitor battery temperature with 'battery temperature guard' app, for all my smartphones.
Battery temperature limit is 45C. In summers, upto 40C is normal, especially while charging and using phone, simultaneously. Using phone while charging heats up more.
Phone will run 5C hotter if you use protective covers, that's why i use protective bumpers.
Your battery is fine, if it's not swelled, even slightly.
To me, it looks pretty normal staying under 40C.
P.S, delete any battery saver apps installed.