Nothing. They could be literally Hitler or literally Gandi for all I know. I'm not in Germany and I don't follow them. The only contact I have is reading French newspapers about how some "far right" party is gaining traction over there. I did note that now that they're gaining more votes, they've become more extremist (according to the same French media). Bonus points for them being considered somewhat "close" to the French RN (which the latter have denied – don't know what that's worth).
My point was rather to note that similar things happen in France, with incumbent politicians trying to convince voters that the French RN is the more extreme the more they gain traction. But pretty much everybody who says anything else than "we should abolish borders and allow any and all immigrants who wish to come" or even "maybe we should do something about crime" is labeled "fascist", "extreme right", etc.
This has been confirmed to me when a French party (LR) which is absolutely not "far right" or anything like that and is actually one of the old "governing" parties, was labeled as such by the left when one of their ministers tried to broach the subject of immigration.
So, I'm skeptical when I see some random mainstream politician, who's party is sinking, call this or that party "extreme right", "fascist", or other loaded terms.
To me this just looks like posturing and name-calling. Nobody tries to prove that this or that party's programme sucks big time on concrete metrics (and they'd actually have a point about the RN). They just appeal to voters' sentiment. Which, after a while, gets old.