My 2017 golf does all kind of weird things. Sometimes it fires up and goes straight to the radio display, sometimes it displays welcome to volkswagen for 1-2 seconds, sometimes it displays it for 5-10 seconds. Sometimes the music is playing while it displays welcome to volkswagen but the volume control buttons don't work, or, my personal favourite, sometimes I get in, put my key in the ignition (do not turn it) then the radio starts up before I even start the car - this one is rare, only had it happen twice now in 4 months.
I always figured there was quite a lot going on in the background even when the car is off and locked, and that it might also depend on whether the car is locked (for instance, in my garage I don't lock the car), but that basically sometimes the radio might be already started up or in a sleep state instead of fully shut down so that the GPS or satellite radio can acquire signal faster.