Is covering your hair before marriage a common reform or conservative practice?

I know that there were some diaspora communities in Muslim countries where Jewish women covered their hair before marriage. Just had never seen it present day in America before this year.

I’ve been seeing this come up on tiktok a lot lately, mostly very young unmarried women who cover their hair daily. Most recently, for example, I came across a video (won’t link it because she’s quite young) of a Jewish girl talking about wearing a tichel going to school.

I was just wondering, has that always been a reform and/or conservative minhag and I’ve bust been living under a rock? Generally I thought that they didn’t wear sheitels/tichels/snoods etc at all.