Many thanks to you all; what do you think of my Vyxal attempt at solving https://codegolf.stackexchange.com/questions/233884/remove-oddly-nested-substrings?
https://lyxal.pythonanywhere.com?flags=K&code=%C6%9B91-%5B%7C0%5D%3B%C6%9B93-%5B%7C0%5D%3B%27%5B%C2%A5%C2%AC%7C%C2%A5%C2%AC%C2%A3%5D%3BC%E2%88%91&inputs=zyx%5Bw%5Dv%5But%5Bs%5Dr%5B%5Bqp%5D%5Bkj%5Di%5Dgf%5D%5Bd%5D%5B%5D%5B%5D%5Bc%5D%5Bb%5B%5D%5Ba%5D%5D&header=&footer=