Flashed with white flash light?

Hey everyone

I've had my license since Monday. I usually drive very carefully everywhere, but just about 20 minutes ago on Castroper Straße in Bochum, I was driving at 30 km/h in a permanent construction zone, and the traffic light turned from green to yellow. I didn't want to miss it, so I accelerated again and was doing a little over 40-45 km/h.

Only the flashing light was white, which confused me because someone behind me flashed his headlights 1-2 times while I was driving up the street at 30 km/h, even though the speed limit was only 30 km/h. I think it could have been him after I crossed the traffic light with the white light.

hope it was nothing to do with red light violation or speeding