Experimental Bluetooth Download not working in V2

Describe the bug

The experimental feature "Bluetooth Download" is not working in micro:bit V2.

To reproduce

Steps to reproduce the behavior:

1. Open this project in MakeCode. It is a test project that prints "Hello World", with Bluetooth configuration "No Pairing Required".
2. Program the HEX file associated to this project to the micro:bit using USB drag and drop.
3. Now open this project in MakeCode. It is a "catch the dot" game, with Bluetooth configuration "No Pairing Required".
4. Enable the experimental feature Bluetooth Download in MakeCode (go to "More..." > "About..." > "Experiments").
5. Reset the micro:bit while pressing A+B (a LED animation appears and then the Bluetooth logo).
6. Go to "More..." (gear symbol) > "Pair Bluetooth" and then select the micro:bit.
7. Check the Bluetooth icon appears in the browser tab. Click "Download".
8. See error: instead of flashing the program via Bluetooth, the HEX file is downloaded to the computer.

This happens just with micro:bit V2. With micro:bit V1, it works as expected.

Expected behavior

In step 8. the program should have been flashed to the micro:bit via Bluetooth.
As with micro:bit V1.

Reproduce the failure with the linked MakeCode projects on a micro:bit V2, following the Bluetooth Download experiment steps and confirming that Download saves a HEX file instead of flashing it. Compare the same flow on micro:bit V1 and trace the Bluetooth Download and Download actions to identify where the V2 path diverges; done means the program flashes over Bluetooth as it does on V1.