I had the same thing happen to me the other day (I have owned my S23 Ultra for over a year now with no issue). I noticed when making a call the other day that the call volume was way lower than it used to be. This was a vary recent development and happened all of a sudden. I don't remember an update happening recently and no physical event happened to the phone or speaker that would have such a large affect on call volume. The media audio was not affected as playing videos and music was still extremely loud through the ear speaker.
What Fixed My Phone:
(I have never before messed with the media volume limit. Ever.)
Called a friend who was able to speak into the phone for a minute just so I could monitor the ear speaker volume. Opened up the volume settings on the phone> then hit the three dots in the top right and selected media volume limit. The media volume limit was off. So I switched it on, slid the limit to max and then turned the media volume limit back to off.
This solved the problem. The phone ear speaker is now as loud as it was previously. Unknown to me if this was a software issue or if somehow this happened in my pocket. (my money is on software)
Anyway hope this helps!
