Hi @Pinkypooh Does the moisture message constantly appear? Moisture does not necessarily mean in contact with water but can be dirt/debris and changes in temperature. However usually does not last too long, however have you tried cleaning to see if that makes any difference. https://www.samsung.com/uk/support/mobile-devices/my-device-displays-a-water-drop-icon-and-will-not-... There can be glitches though and if problem continues will need to get it checked out.
With the Bluetooth headphone issue can you try switching Bluetooth off/on unpairing and then pairing again,you may also need to reset the Network connection. See information here https://www.samsung.com/Bluetooth Advisable to run the Diagnostics tests to see if anything highlighted there though via Samsung Members-Get Help.
If all else fails may need to visit an Experience Store or Samsung Service centre.
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 4.0,Android 12 Official Version.