@stefan Those “tool free” connectors are very common nowadays. biggest problem with those are the longevity. After using them three times they are prone to breaking and (as you just stated) the same clip opens up both sides of the connector, so it makes it finniky if you aren’t used to.
you could replace them with WAGO clamps but those are usually a little bit bigger, so they might won’t fit and they are quite expensive.
@stefan Well, if that is your choice of colours, I’d prefer the stickers. 😜
https://www.elektrofachkraft.de/sicheres-arbeiten/farbliche-kennzeichnung-leitungsadern-tn-system