Cached page displayed instead of the one being served from the server

Linux Mint 20.1 "Ulyssa", Apache, Mozilla Firefox (from repos)

Any reason why after editing a few files on the server Mozilla Firefox or Apache (?) ignores them and pushes cached version of the page, not the one currently being (supposedly) served? Haven't had any issues for like .. ever ..

If I open the page in incognito mode, I do see changes, but not if I keep using the main browser window (even after closing the tab and opening again).

Why is this happening and most importantly - how do I "fix" it?

Have your edited files got unique names?

Had lots of caching issues in the past because I was replacing files in a folder with a new file with the exact same name.

Well, no. That's the trick. I have only index.html and style.css. I'm editing them directly, not replacing. As I said, I haven't had any issues for like .. ever. Now all of a sudden I can hang myself, but changes won't be served.

Try to refresh the page by using Ctrl+F5 instead of a normal refresh.