I don't want to start a "who did it first" because I don't know for sure, but given when this was posted, it feels wrong not to mention Tito Ferradans [0][1] at all. From what I can tell, he is the one who really popularised this mod and if you're interested in getting that anamorphic look on a (relative) budget, his channel is full of great tips.
[0] https://www.tferradans.com/ [1] https://youtube.com/c/AnamorphicOnABudget