In the Premier League for example, the typefaces used for the names and numbers on players’ shirts is the same. When those same clubs play in Europe, though, they go back to their normal brand-associated design standards. Aston Villa, Manchester City, and Liverpool are 3 examples that have distinctly different typefaces for the names and numbers than the Premier League’s version if you need a visual reference.
Is there a reason leagues have their own styles for shirts? Why don’t clubs just wear their normal kits that they would wear anywhere else?
Each club have their own unique style and fonts. It’s just premier league mandates a certain typeface for premier league matches. (Others have explained why)
If you see club friendlies, clubs will use their own fonts and numbers. Also buying from official merchandise store, you can choose which style of font you want on the back. Either the clubs font or the premier league font. Sometimes they will have different European competition styles too.