Some people, when confronted with a problem, think “I know, I’ll use regular expressions.” Now they have two problems.
Oh yeah they definitely have uses, but there’s a real tendency for people to go a bit crazy with them. Complex regexen aren’t exactly readable, there’s all kinds of fun performance gotchas, there’s sometimes other tools/algorithms that are more suitable for the task, and sometimes people try to use them to eg. parse HTML because they don’t know that it is literally impossible to use regular expressions to parse languages that aren’t regular
It’s entirely possible to parse HTML in PCRE. You shouldn’t, but it is possible. The language stopped being strictly regular a long time ago and is entirely capable of doing it.
I’ve once written a JS decompiler (de-bundler?) using ~150 regex for step-wise transformations. Worked surprisingly well!