Bug since 2016.
By tuning your wifi settings you can decrease the “offline” occurrences.
Mostly only the app thinks Homey is offline / can’t reach Homey; that’s why I consider it to be a bug.
To check what’s really happening, install the Net Scan app and have it monitor your router’s IP address. It probably will detect (way) less offline states compared to the number of offline events the Homey app presents to you.
Wifi optimisation hints (goes for Pro 2023 as well):
