Does a video show Ukrainian children singing the unofficial anthem of the Luftwaffe? No, that's not true: They aren't singing a Nazi German air force song. The song is by Bots, a Dutch folk rock group.
The claim appeared in a tweet (archived here) published by AZmilitary1 on September 23, 2022. The tweet opened:
Nothing unusual, just Ukrainian children singing the unofficial anthem of the Luftwaffe - the Wehrmacht Air Force of the Third Reich.
This is what the post looked like on Twitter at the time of writing:
(Source: Twitter screenshot taken on Fri Sep 23 15:02:12 2022 UTC)
Directly under its tweet, AZmilitary1 posted another tweet that purported to include a link to the "original song." That link takes users to this YouTube video.
Although the title of that video reads "National Anthems Air Force the third reich luftwaffe," the actual description in Russian says the song is not the official anthem of the Luftwaffe. Below that, it correctly identifies the song as "Zeven Dagen Lang," a song by Bots, a Dutch folk rock group popular in the 1970s. (For context, the Luftwaffe was disbanded in 1946). The pop group also recorded a German version of the song, "Sieben Tage Lang." Both titles roughly translate to "Seven Days Long."
You can watch and listen to Bots's versions of the song below: