Suppose you freshly installed Linux alongside Windows in the same machine, then there are several "sync" issues need to be taken care of. The solutions has been tested in my specific cases of pop_os! and Windows. They should work for most distributions.
Time not in sync1
For timezone, Linux calibrates clock according to Universal Time Coordinated (UTC), whereas Windows uses local time from your location. Thus, if you reboot into Windows from Linux, you will see that clock differs by several hours - Windows has incorrect time. The most straight forward way is to fix it within Linux to let it read local time:
sudo timedatectl set-local-rtc 1 Bluetooth not in sync2
Shout out to power users spxak1 and x2es!
If you would like to use the same bluetooth device, say headphone, on both OS, you need to tweak a bit after initial pairing for each OS. Out of the box, after paired on Linux and then paired on Windows, boot back to Linux, you will find the headphone is not working.
Bluetooth device, once initially paired, generates a unique key, and this key does not sync between different systems. Thus, we need to sync it manually, preferably working from Linux terminal, if you do not want to mess with Windows registry.
spxak1 detailed the guide using
chntpw here.
Once followed through, my headphone Sony WH-1000XM5 worked for both Pop_os! and Windows
without re-pairing!
Alternatively, x2es has written a Python program to automate the process, but it did not work for me. Try it yourself!