The most nazi thing in the links you provided were the government banning certain slogans.
What is your definition of nazi as that will probably explain a few things.
You had use of a banned slogan. A nazi accusation, party memeber leaving due to claims of right wing infiltration.
None of that is evidence of them being nazi's. Sus for sure but pretty weak.
I just did another quick google search regarding the somewhat recent arrests from that attempted coup. Albeit they were former members of the party so i guess too extreme for the AFD. And well not very competent or numerous.
But thats kinda something.