I put this site into git for the first time last week. Nothing unusual about it - a new repository, a list of files to leave out, one commit.
Before committing I read the warnings. There were about a hundred, all saying the same thing: git was going to change the line endings in my font files the next time it touched them.
Fonts aren't text. Changing the line endings in one doesn't make it render badly, it stops it being a font.
Why it happens
Git has to decide whether a file is text or not, and it does that by guessing - it looks at the start of the file and sees whether it reads like text. Compressed files like fonts can easily look like text for the first few hundred bytes.
I think it only becomes dangerous on a setup like mine, where I work on Windows and the site runs on Linux, so there's a conversion sitting there waiting to happen. On a Linux-only machine it probably does no harm at all until somebody else clones it.
The fix is a small file called .gitattributes that lists the file types git isn't allowed to guess
about. Fonts, images, video, PDFs. Two minutes.
I got lucky. The warning was there, buried in a hundred identical ones, and I happened to read them before committing rather than after. If I hadn't, the fonts would have broken on the live site weeks later - and the history would have looked completely clean, because the damage happens when the files come out of git, not when they go in.