Maybe it's just on my side but the l's in the flipped "all" seem to be either displayed upright or not at the correct height. Which would only support the linked article.
The flipped text is doing a trick where you pick things from Unicode that merely look like upside down Latin letters. Some of them deliberately are exactly that for whatever reason, some aren't. So the effect isn't exactly perfect and shouldn't be. There isn't actually a plain text way to say "for some reason render this upside down" because like, why.
Alright, makes sense. Regarding the "why", well, Unicode has a lot of weirdness already. Like the subscript/superscript characters that don't cover any complete alphabet. And after seeing various tricks like t̢̬̯̮̥͋͒̔̾̽͘͟ḥ̛̙̟͍̦͉͔̤̝͔̪̮̳̠̩̗͔͕̽̐̏͟͢i̔̊̃̌̆͋ͫ̏̽ͧͪ̂҉̺͚̺̤̳̥̰̬̻̜͈̦̰͙̲͘ͅs̢̓̾̎̃͛ͧͪͬͨ̍͂ͩ̅̑̎͌̚̚͏̗̙͚͉͢
not much surprises me anymore.
Unicode's goals include subsuming all prior existing text encodings. That means ASCII and ISO-8859-1 of course, but also really obscure encodings that maybe only were ever used on a handful of machines. The idea is if your project isn't using Unicode, the reason shouldn't ever be "Oh we need this obscure character - we use it for compatibility with our 1978 Huge Corp X42 mainframe but it isn't in Unicode".
This is often the reason why character X is in Unicode but seemingly equally useful character Y isn't. At some point somebody put X in an encoding on some archaic hardware you've never seen, but not Y. In this sort of case neither X nor Y are things you should emit if you don't need them, but they're in Unicode in case somebody finds a pile of Huge Corp X42 tapes and wants to convert that to Unicode.
In cases where both X and Y, and even the more obscure Z are encoded, chances are Unicode has them all because humans (not just some obscure computer hardware from the dark ages) used X, Y and Z to write stuff, and another Unicode goal is to be able to encode all human writing systems. The over-abundance of combining forms you abused on your word "this" is almost all for that reason.
Those are actually just regular l's, and the "upside down n" is just a regular "u". The more interesting letters are from the Unicode IPA Extensions range: https://unicode-table.com/en/blocks/ipa-extensions/
