Modern conservative ideology in the US and Europe is entirely irrational and unappealing to younger people who have even a modicum of real world exposure. As such, conservatives have had to accept that they cannot win support from newer generations on the merits of their beliefs and opinions, and their core demographic is aging out. The alternative is to simply remove the availability of conflicting worldviews altogether. They can't win the argument, so they want to prevent people from being able to have it at all.

This is also why Republicans have recently started calling for raising the voting age. 18 year olds are coming to voting age in a world where they fear for their lives and where they see their freedoms being eroded. The Republican position on this essentially amounts to "yeah, and?" Which isn't a particularly compelling argument to support them. So the GOP's solution is to just remove the voices of the people they disagree with.