I found a strange issue while testing on itch.io on Firefox: when I open the app in a new tab, it resets the title and text, so they are empty. This does not happen if I open a new window and paste in the address, but it does happen if I open a new tab and paste in the address. Right-clicking the "play notepad" link from this tool jam rating page and opening the link in a new window does the same thing (saved state is lost). It's very odd. Because I'm entering my comments in one tab, and opening the app in another tab, at first it seemed like saving did not work at all.
I tested a project of my own that does more or less the same thing (it uses localstorage to save the text typed into in a textbox, as it changes, and recovers that text when reopening the page after it loads), but I didn't encounter any issues there. So it doesn't seem to be specifically a Firefox issue. One difference is that my project is hosted on github, rather than itch, but it's hard to tell if that's definitely part of the issue without further testing.
Does this make any sense?