Well, if I were, say, typing up a forum post, that would be lost. More often, however, I simply lose all my tabs. Which are not impossible to restore, given Firefox's "Restore Previous Session" button. But since I have the Cookie AutoDelete extension[0], all my sites get logged out. So I have to re-authenticate with my password manager, log back into all the sites, half of which require me to pull out my 2FA token...

It only takes about a minute total to get back up and running on everything. It's just a nuisance when it happens.

[0]https://addons.mozilla.org/en-US/firefox/addon/cookie-autode...