UPDATE:
Today, I visited a K-tuin store (an official Apple reseller), and they told me they had no record of that issue. I played the same song on an iPhone 16 Pro Max they had on display and compared it with mine, and that one didn’t have the problem. So, in principle, this issue has a solution.
Therefore, I recommend that you all reset your phone to factory settings. I’m going to try doing it tomorrow or in the next few days to see if it works. I don’t think this issue will be fixed with a software update.
Likewise, I’d like to remind you that this forum is not a place for Apple to fix anything. If you have an issue, you should contact technical support and report it, because this forum has no reach.
If the problem persists, I will go to an Apple Store to see if I can request a phone replacement. Lastly, I’d like to remind you that your device has a one-year warranty, so don’t wait until the last minute to address your issue.