In 2016/2017 there was much more awareness of Russian interference than there is now. The protests were more about legitimacy than about disagreement or dislike.
By 2021 the Putin/MAGA forces had accreted so much power that it was safer for Republican senators to bend the knee and acquit in the impeachement trial.
Putin is playing with fire manipulating elections that put borderline fascists in power. Especially in the US. He might be in for a dissapointing surprise. We shall see.
The only way to win against the US is to divide it from within and/or obtain its non-involvement. By the time they send a carrier strike group, or worse, troops, it's game over. So that's what the Kremlin is doing: the thing that wouldn't have worked during the Cold War because the commie agitators would have either ended up in prison or being constantly harassed.
By 2021 the Putin/MAGA forces had accreted so much power that it was safer for Republican senators to bend the knee and acquit in the impeachement trial.