Hi,
Do your problems resemble this topic?
A new A15 update for the FP5 came out today. It might be worth checking that out before anything else, even if the changelog doesn’t mention Bluetooth.
When the problem occurs, rather than restarting the phone, try just turning Bluetooth off and on again (use the pull-down quick settings pane).
If this is a Bluetooth problem then it might be worth doing a Bluetooth and Wi-Fi reset.
Warning : this will cause your phone to forget all the Bluetooth pairings and Wi-Fi networks (especially their passwords, so have those ready for when you need to reconnect).
To do the reset, go to
Settings > System > Reset options > Reset Bluetooth and Wi-Fi.
P.S. - and welcome to AnneLN