I remember seeing or hearing about this some months ago, the Romeo app statistics thing, although I don't recall where.
It makes sense when you reject the mass media framing of AfD as Far-Right. In actuality, it's chiefly classical liberal or libertarian but with 20% or so of its members being, let's say, Far-Right or Far-Right-adjacent. Either way, that leaves the overwhelming majority of the party as essentially non-Rightist or only barely Right-leaning.
For instance, Peter Boehringer openly identifies as a liberal, says that he opposes Nazism because it is 'socialism' and he is not a socialist, and says that he's a Centrist who is only regarded as a Rightist because Germany's politics have changed, not his.
Likewise, the dyke Weidel says that the AfD opposes Nazism because it is 'authoritarian socialism' and the AfD supports 'libertarian capitalism'. So therefore the AfD is, in this framing, sort of the opposite of National Socialism.
German politics has shifted Leftward enough that Centrists and Rightists are essentially pigeonholed into the same category, hence why the AfD is a sort of big tent, its membership roughly 80% Centrist to Right-leaning and 20% Rightist to Far-Rightist.
Unlike Leftists who view all of this as politicking, I think that only idiots don't take them for their word. When they say that they are Centrists, libertarians, liberals, and the like, they actually mean it, and all the nonsense to the contrary just comes from paranoid Leftists on the one hand, and misguided, wishful thinking from Rightists, on the other.
This isn't just why the Romeo statistics make sense, but also why AfD having an LGBT wing and a yiddish wing make sense. Just accept what they tell you they are rather than what their enemies tell you they are, and any supposed 'contradiction' about the AfD goes away. Contradictions only appear when you believe the misinformation: 'Why would a plurality of Romeo users support the Far-Right?' Just forget the notion of them being Far-Right and this question doesn't come up. Likewise with the idea of LGBT supporting Nazis. Just throw the 'AfD equals Nazis' narrative out of your mind and this seeming contradiction is dissolved.
Needless to say, if I were a German voter, I'd probably vote for III Weg (Volkisch, non-National Socialist) or possibly Homeland (close to National Socialism), whereas I view the AfD as essentially the CDU of a few decades ago. Just as I wouldn't be voting for the CDU of Helmut Kohl in the 1980s and 1990s, I wouldn't be voting for the AfD in the 2010s and 2020s.
As for the Romeo users, they're probably just the ones who haven't fallen for the misinformation. They may see that the AfD is the only major German political party with an LGBT leader, for instance, and so it makes sense that some might see the AfD as 'their team' because of observations like that.
What is new to me looking at this graph is how similar the Romeo users are to the general public. If you take the average German voters, the percentages aren't that different from what you see here: AfD and Die Grunen most popular, BSW and FDP least popular.
BSW is interesting in that it had a lot of hype surrounding it when it first appeared: the mass media attacked it as 'anti-immigration', 'Left-conservative', and 'pro-Russian'. But rest assured that it isn't even on the level of the AfD. The AfD leadership is at least mostly ethnically German, whereas BSW has many mixed and outright non-white leaders. As for immigration, I don't even think that BSW wants deportations of any kind, including of illegals. Thus, I don't think they differ from the pro-immigration parties in practice.
The worst political party is almost certainly Die Grunen, with their blatant Antifa, feminism, and LGBT promotion. Their party propaganda is repellant, painting a purely degenerate (and very non-white) urban hellscape that just happens to have some plants in it, reflecting the fact that their environmentalism is just a sort of afterthought bolted onto their socioculturally extremist primary agenda.