Update March 22, 2020:
I saw that the following command could help in some cases:
sudo defaults write /Library/Preferences/com.apple.airport.bt.plist bluetoothCoexMgmt Hybrid
(Explanation on Stackoverflow)

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I thought I was done with this from my previous post about it. However it didn’t last long and the problem re-appeared later. It was not as bad at it use to be but not 100% fixed.

Then I decided again and I found this interesting YT video (credits to Bikman Wei) around the topic. After going through the steps provided the issue didn’t re-occured.

Steps

Download XCode & install

https://apps.apple.com/us/app/xcode/id497799835?mt=12

Download Additional Tools for XCode

https://developer.apple.com/download/more/?=Additional%20Tools%20for%20Xcode

Select the the Additional Tools for XCode (formely Hardware IO Tools)matching your version

Open Bluetooth Explorer

1) Open the Additional_Tools_for_Xcode_[version].dmg file
2) Go to Hardware > Bluetooth Explorer.app
3) Once Bluetooth Explorer app started, go to Tools > RSSI Sweeper

Execute RSSI Sweeper

1) Connect your bluetooth device (in my case the Sony headset WH-1000XM2)
2) “Start” the sweep

Your bluetooth devices will get disconnected during the process

2) Click “Force Restore”
3) Restart your Mac

Your bluetooth devices will get reconnected after the reboot and hopefully you won’t struggle with any connection drop anymore ;)