I was troubleshooting Bluetooth connection today and I thought that this is somehow related to software (PipeWire, bluez, bluetoothd and all that stuff). But no. Apparently Bluetooth barely works when WiFi antenna is disconnected from my ASUS motherboard.
Anyway, this might save a lot of time for someone, so I’m posting it here.
To add: Bluetooth and WiFi both use the 2.4ghz spectrum. They are on the same chipset because otherwise you would need two antennas