Why does my status keep changing to online?

[Stellar Remnant]

I have it set to offline on purpose, but it keeps randomly changing to online... this is infuriating.

[Jerry]

I suppose, the Steam task has hiccups and tries to reconnect you at those times. Should not happen, but well... Steam.
Want to use Invisible mode instead? You'll still appear offline to everybody, except for those, you contact by yourself.

[Iceira]

Its not that simple anymore, any dl hang in cue or in-game own web look up stuff can trigger go online.

if you want to stay in offline mode today, then get a MS 169.254.x.x ( with no network attached )
pc work best with either that or be online, things in the middle can hammer the door and get laggy as hell.