The letter definitely dates from 2021. Second line one can see 2021. And it starts with "Ich habe mich (...) etwas Zeit (...) 2021 gelassen. " i took my time? Since ... 2021? Possibly "i took my time to write back to your letter dated something something 2021"? I think I have cracked his handwriting but my German is not that good as to fill in the gaps...^ That's an interesting thought too. I expect the Sat1 doc will provide info on when the letter dates from.