Another, more recent, statistic[2] bears this out, 54 kg, and also has surprising (to me) details. Of those 54 kg, fully two-thirds -- 38 kg -- are processed potatoes (the article names potato chips/crisps, ready-to-eat potato salad and, of course, fries) and just 16 kg are "real" fresh potatoes.
Finally, things used to be different[3]: in 1950, the per-capita consumption was 186 kg!
[1] https://landgeist.com/2021/12/21/potato-consumption-in-europ... attributed to FAO
[2] https://www.bmel-statistik.de/ernaehrung/versorgungsbilanzen... German dept. of agriculture
[3] https://www.statista.com/statistics/539799/per-capita-consum... it doesn't say, but I doubt people were eating a lot of potato chips in 1950 Germany