Why does glitch text look broken on some devices?

Heavy glitch text is many stacked Unicode combining marks per character — some fields cap length by byte count, and some fonts don't support every combining mark, which is what causes trimming or box ("tofu") characters.

Each visible "glitched" letter is really a base character plus several extra Unicode combining marks stacked on it. More marks means more bytes and more code points per visible letter — and some apps and older systems cap text fields by byte count rather than by what looks like one character to you.

Separately, not every font on every device includes glyphs for every possible combining mark. When a system can't find a glyph for a code point, it shows a placeholder box (often called "tofu") instead — this is a font/rendering gap, not a bug in the text itself.

The "through" marks (strikethrough-style overlays) are disproportionately likely to trigger both problems, which is why this site's generator gives that zone its own independent slider — see the glitch font generator and its renderability badge, which estimates this risk before you paste.