As has been mentioned Bluetooth should only be switched on for Devices or Apps which require it. Whilst not likely to be a great deal of battery drain discopnnecting when not required will avoid possibilty of unwanted devices connecting. see some information in this article https://www.androidauthority.com/does-bluetooth-drain-battery
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.