Hello,
3.5 hours of screen on time is not normal. You should have at least 7 or 8.
https://eu.community.samsung.com/t5/galaxy-s24-s24-s24-ultra/batterijduur-verbeteren-op-je-galaxy-to...Please look if these tips help you.
Also please go to settings > device care > battery > Click on the graph > scroll down and make screenshots of all the apps that used battery and post it here please ( do this when the battery is almost empty )