Are you using YouTube or another App @Liam4 ?
You could initially try clearing the Apps Data and Cache.
If no joy then shut the phone down and then from a set series of button pressess that takes you into the phones file system and clear the system cache. This will not delete your own saved info in the phone.
If no joy try backing up and factory reset.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.
