@nazhus 

Check if you have enabled or created the below settings that might lead to this situation.

1. Schedule, Away mode on the Tapo app. How to Set up Schedule, Away Mode, and Timer for Smart Plug/Bulb/Switch in Tapo App
2. Automation rules that involved the smart bulbs. How to create Tapo Automation
3. Schedule, routine, or automation on third-party apps like Alexa, Google Home, SmartThings, etc.

To rule out whether the settings are causing the abnormal behavior, you can try restoring the bulb to factory settings. When reconfiguring the bulb, give it a different name (in case the old settings take effect based on the name), and see if the problem still occurs. How to reset Tapo bulb

Regarding the "unpair" issue, does the smart bulb show offline in the App? Do you need reset it first before adding it back to the App?