Depending on which Linux system (Kernel version) you are running, bluetooth may not work properly.
Have you tried to fully delete your Fairbuds from the BT stack and re-register and thrust them again?
I twice had the problem after a kernel update. Bluetooth did not work properly anymore. The first time I had to wait for the next kernel update (LMDE 5). Now again with a problem after a new kerne update (meanwhile LMDE 6) I could get it to work again using pulseeffects and play with buffer values.
I’m curious for how long I can rely on it again.
I may have found a workaround for those that are affected. It looks like blueman has difficulties connecting to the fairbuds. I have solved it with KDE’s Bluedevil.
You have to install Bluedevil, and run bluedevil-wizard from the terminal. Then search for the fairbuds. If you get a pop-up with a code, just connect to it. And it works.
Hope this gets fixed in the future, and i hope this work-around works for everyone