My guess is that with non-left political movements on the rise better surveillance tools were needed to prevent them from winning the elections around europe.

I really don’t but any other reason, as other tools (legal and technological) are already in place.

If you look at who voted for chat control approval you would find that it's majority the currently in power centre right parties. The more far right or left you go the more likely they were against. It's like the one issue where AfD, die Linke and Greens are aligned. That suggests that it's most likely hard lobby that bribes the established class.

Nt being able to scan personal communications would break big tech platforms main monetisation strategy (selling peoples data).