With my BT headphones, a range of 10 m is specified. When I use my Bluetooth headphones at home on my laptop, the signal is good and I can often go to another room that is further than 10 m away without the connection suffering.
But when I use the headphones on my cell phone (whenever I'm on the go), the connection is worse. Often the music then stops.
What could be the reason?
I suspect that it is because the Bluetooth transmitter on your PC is stronger than that of your cell phone.
In addition, when you are out and about, many other signals in the same frequency range interfere with your headphone signal.
Can I do something about it?
No, hardly
If the interference is as strong as you said in your question, you will have these problems with 500 euro high-end headphones as well as with 5 euro headphones from China.
The only possibility that I see in your case would be branded internal headphone-mobile phone combinations such as IPhone + AirPods
The audio files are transmitted via a Bluetooth-WLAN combination (Apple's "AirDrop") to prevent interference.
Each device has its own transmit and receive power. So there are "strong" and "weak" devices.
