Using the glitch generator
Type on the left and the broken version appears on the right. Style picks between struck through, where every letter carries a bar, and mixed blocks, where each letter is pulled from a different corner of Unicode.
Swap the boxes to go the other way. The tool knows all the letters it hands out, so it can take them back.
Where the broken letters come from
Most of them are ordinary letters in somebody's alphabet. Ħ is Maltese and starts the word for a shop. Ø is Danish and Norwegian, and it isn't a zero. Ł is Polish, the first letter of Łódź. Ŧ writes Northern Sámi.
Reading them as damage is our idea, not theirs. A Maltese reader sees a consonant where you see a corrupted H.
Five capitals have no struck letter anywhere in Unicode, so the tool borrows a currency sign shaped like them: ₦ for N, ₩ for W, ₴ for S, ₣ for F and ₥ for M. The naira and the won carry bars for the same reason the letters do, to say this glyph means something other than the letter it's built on. ₥ is the mill, a thousandth of a dollar, which survives in American property tax rates and nowhere else you'd notice.
What happens where Unicode has nothing
The rest get a line drawn on. U+0336 is a combining mark that renders as a stroke across whatever came before it, and it's the same character the strikethrough tool uses. So s̶ is a plain s wearing a line, while ŧ is a letter in its own right.
The currencies are capitals only, and that's a decision rather than an oversight. There's no lowercase naira, so ₦ would have to stand for both n and N, and your sentence would come back from the tool with the wrong case in it. Lowercase takes the line instead.
Nothing is left plain. Half a glitched word reads as a typo rather than an effect.
Related conversions
Weird text is the mixed-blocks style with its own page and a longer explanation of which blocks it raids. Cursed text goes at the problem from the opposite direction, leaving the letters intact and burying them in marks.
Paste any of it into the Unicode converter to see the code points, which is the quickest way to prove Ø really is a letter.
Questions
Is glitch text a font?
No. Every character is a real code point, so it keeps working when it lands somewhere that allows no formatting, like a bio or a username field. Nothing needs to be installed.
Why do some letters look struck and others look crossed?
A letter that exists in Unicode with a bar already, like ħ or đ, is swapped for that letter. One that doesn't gets a combining stroke laid over it, and renderers draw that slightly differently.
Will it work in a Discord or Instagram name?
The barred letters usually survive, since they're ordinary letters. The combining stroke is the part that gets stripped, because platforms filter combining marks out of names.
Can I get my text back?
Swap the boxes. Every substitution reverses and the strokes are dropped, so the original comes back exactly, case included.