Why is my TP-Link UB500 v2.8 USB Bluetooth dongle not working on Debian 13 Trixie (Linux 6.12.12)?

I bought a new TP-Link UB500 v2.8 Bluetooth USB dongle and connected it to my Debian 13 Trixie PC (kernel 6.12.12). The default KDE Bluetooth manager (bluedevil), is able to search and show the device. But when I pair any device, it gives an error: The setup of has failed I then installed Blueman (another Bluetooth manager) When I pair with that, it is able to pair with it, but gets disconnected after 2 secs. Even this is highly finicky, sometimes it won't pair too. General search indicates that it might be using a realtek RTL8761B chip. The PC is using the debian povided latest Realtek driver

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