Netflix downgraded me to Ads

I opened Netflix yesterday to it asking me a bunch of demographic questions for the purposes of showing targeted ads. I didn't think anything of it and continued on. I got wondering and looked at my current plan and it showed I had the ad supported plan. I've never had an ad supported plan, never seen an ad on Netflix. I've had the premium plan since I signed up years ago and have been billed monthly for it. I live alone, no one else uses my account. I ended up changing it back and Netflix acted like this was some new switch.

In any event, I didn't switch to ad supported myself. I also didn't receive any email telling me my plan had been changed to ads like I did when I switched back to premium. Just to be thorough I changed my password, though seems like a wonky thing for someone to use my account without my knowledge and change to a lower subscription tier.

I don't understand why this happened. Anyone else experience this recently?