iphone 16 Pro sound automatically switching between speaker and ear-speaker

My iphone 16 pro, which I purchased in Feb, 2025 started having an issue where the audio was suddenly switching from the speaker to the earpiece.

When watching any content like an instagram reel, the audio first comes from the speaker and then switches immediately to the earpiece. Same with youtube videos or any other sounds coming from the iphone. I checked the audio settings and the accessibility settings, but doesn't seem to work for my case. Restarting the phone temporarily fixes the issue, but starts switching the audio automatically after a few minutes.

In the music app, the airplay option where can change the audio output, I have observed that when the audio is coming normally, it says "iPhone Speaker" and when the audio switches to the ear-speaker, it says "iPhone" as one option and "Speaker" as another option. Even the sounds when locking the iphone are also coming from the ear-speaker.

Please let me know if anyone has a fix for this.