I have been facing this issue for sometime now; wondering if anyone also faced it.
Before I tell you what is exactly happening I want you to know that this challenge was also experienced with IOS 14.4.1 and earlier. I have 2 changes in the settings for BackTap; double tap to turn WiFi off and tripple tap to turn BlueTooth off. In order to perform these gestures to work; phone should not be locked by which I mean it should be in wake mode or unlocked.
What I have been experienceing is randomness when handling the phone; Bluetooth or Wifi gets disconnected and this seems to be triggered due to the device accidently registering the BackTap gesture. I can say this confidently as the BackTap gesture triggers the 2 shortcuts I have made to do those tasks. If I want to actually disconnect WiFi or Bluetooth; I have to use my index finger and tap really well for the gesture to register and the shortcut to be performed. However, randomly when I am in the middle of something and have not performed the gesture; my WiFi aor Bluetooth gets disconnected. This is very strange behaviour and wonder if it is something wrong with the device that was shipped to me.
PS. I have the iPhone SE 2020