The translation for "Chain" in German is "Verketten". That is incorrect, it should be Kette. 

This is NOT an issue that can be fixed on Crowdin, since the string is missing there on the 1.16 section.

It looks like, the translation is taken from the string "advMode.mode.sequence" from Minecraft 1.15, which is "Verketten". (see here: 

However, chains were added in 1.16 and there is NO string for the Chain (Block) in Minecraft 1.16 (or 1.17) strings.

You can't use one string for two completely different things where one got added over 5 years ago and means something completely different.

Here you can see that there is NO string for the chain (block) in German.

https://crowdin.com/translate/minecraft/9435/enus-de?filter=basic&value=0#q=chain