Hi @Nick65 , you can find many solutions here, i prefer give you the link because it's many pages to read
To help others people, please come back and tell me wich solution work for you...
Changes in weather.condirions can set this off @Nick65
Usually the warning goes after a few minutes.
If this continues then a Samsung Experience Store / Samsung Service Centre can run a diagnostic test on the phone.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.