Obviously, I have no idea statistically which one we receive more of. However, speaking from experience, we appear to get a ton more of user's sync data getting removed.
The most common is usually that the user reinstalled Windows 10 or sold their computer to buy a new one and expects that Sync will rebuild their entire Firefox profile for them when they login. For example, my most recent thread I participated in involved someone who bought a new system, trashed their old one and then wanted to recover over 500 bookmarks which included 1 year of research for their job. They hadn't made a backup before trashing their older system because they misunderstood the purpose of Firefox Sync.
That's not to say that we don't get threads about password resets erasing data, although I would say they are much less common, primarily because the user is warned of that fact before they request a password reset. I don't feel that the password reset case requires any action, since it's a logical privacy protection move that shouldn't impact the average user.
The more common issue along those lines is a user that lost their 2FA device and didn't copy their recovery code, so they've lost access to their account. But that's a separate issue from the one mentioned in this bug and a situation where I feel the responsibility falls more on the shoulders of the user.