If it were anything other than a standard zebra crossing, traffic would certainly have to be informed of the atypical priorities.
In the image you posted, I see only two signs which could tell us anything. One is the blue circular sign level with the crossing, which is just about recognisable as StVo Zeichen 240. This indicates a gemeinsame Geh- und Radweg, or a combined pedestrian and cyclist path. It does not indicate or imply any special rules for crossings.
That leaves just the square sign, attached to a post at the edge of the bushes, shortly before the crossing (from the direction of oncoming traffic). This sign is, sensibly enough, pointed towards oncoming traffic. Unfortunately that means we can't actually see what it is. However, the shape already drastically limits the possibilities, and considering its location there can be no meaningful uncertainty that this is StVo 350, Fußgängerüberweg (pedestrian crossing). There are no Zusatzzeichen providing any further information, so I can only conclude that this is a standard zebra crossing.
So: how to handle it?
As you correctly say, German law gives priority at a Fußgängerüberweg to pedestrians. You're not required to dismount, but if you remain on your bike there is no obligation for traffic on the road to stop and allow you to cross. If you dismount, you are a pedestrian and road traffic must stop to let you cross.
Nevertheless, in my experience many drivers will stop and allow cyclists to cross. Approach at a speed that allows you to comfortably stop before entering the road, and judge whether it is safe to do so. If you're confident that it is safe to cross, by all means cycle across. If you're not certain you can cross safely, then it's up to you whether you dismount (thereby gaining right of way - of course, you should still ensure traffic is actually stopping before you go) or wait while still on the bike. Personally, I never dismount and I don't find that I wait any longer on a bike than I do waiting at the same crossing without my bike (whether that's because most drivers don't know or don't care about the difference in priority for cyclists vs pedestrians isn't for me to say).