Hey there, have you tried to do network reset on your phone? It might be due to numerous reasons. My one at first was dropping signal really badly but then I got in touch with my network provider and it was the case that they have some issues around my area. If not have you tried to wipe cache partition?
It may be caused by oxidation, dirt, or static build up on sim card. Remove your sim and give it a gentle clean on the contacts side with a pencil eraser and then put back in. Sometimes the simplest solutions are the best. Let me know how you get on.
My S24+ keeps dropping signal since update on 21.09.2024. It's so annoying! And the whole time it's showing that I have signal, but at the same time gives me "only emergency calls".