Judicial activism is striking down any law that was duly enacted by the other two branches, or overturning any conviction from a lower court.
Sometimes it's called for, sometimes it's not.
Roe v Wade and all other abortion cases up to Dobbs are judicial activism. Dobbs is judicial passivism, and it was called for.
Alito's ruling in Rucho v Common Cause was also a passive decision, but, not called for. The facts and law were pretty clearly on Common Cause's side, and the court majority literally pretended not to understand basic addition to arrive at their conclusion. Nonetheless, a passive court is not necessarily a bad thing because there are other ways for the people to check bad actors besides federal court cases, as Alito pointed out at the end of that decision.
However, Alito has telegraphed that he intends to write a very activist decision in Moore v Harper, and that he intends to contradict what he signed on to for Rucho as he does it. He intends to close off all remedies against a runaway state legislature, other than voting out the members in their gerrymandered districts which of course will never happen.
So yes, there is a very serious right wing judicial activist threat to the republic, at the moment. Certain Republicans are trying to make themselves totally unaccountable to the people.

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