That happened because Americans developed a general paranoia of the government, and since the GOP was better at mobilizing the paranoid vote than the Democrats they started losing rights.

People in the US are generally angry at the Democrats for being incapable of doing anything so they voted for Trump in the false hope that things would change. Or not voting at all because the internet told them the whole system is broken (PP kind of messaging). But I guess changes happened, but not anything positive.

The left seems have become more like what conservatives used to be like. Opposing the government on any change in favour of symbolic traditionalism.