Mostly Eurowings, Ryanair, TAP, Alitalia, Aegean, British Airways, Austrian Airlines, Lufthansa, Iberia, Condor, Thomas Cook, Finnair.
I am yet to hear that I can turn Bluetooth on after the security debriefing and even though I fly regularly, so far just boarded like two flights where there was on-flight wlan available.
You have to turn everything off for takeoff and landing, but inbetween it's all fine - the only difference left between airlines is whether they'll leave people use airplane-mode during takeoff. But don't ask attendants - regardless of actual regulations, when in doubt on a technical point they will always err on the side of caution and tell you to shut it down.
It's not even because of the risk of interference - it's just that if everyone has their electronic devices out and there is sudden turbulence, or worse still, a crash, they become projectiles that cause further injury - laptops especially.
The rules changed fairly recently, but lufthansa.com now says:
> You can use your Bluetooth headphones during the entire flight without restriction – even during take-off and landing, unless the crew instruct otherwise.
britishairways.com:
> Bluetooth devices, e.g. wireless keyboards or headphones, can be used during the flight but must be switched off for taxi, take-off and landing.
I believe that Bluetooth was prohibited on Lufthansa as recently as 2017, so it might be worth to check for each airline you're using.
If you're on a Lufthansa flight I'd recommend reading the safety card or the in-flight magazine. One of them usually mentions BT is allowed at cruise altitude.
I am yet to hear that I can turn Bluetooth on after the security debriefing and even though I fly regularly, so far just boarded like two flights where there was on-flight wlan available.