Achievements gained, while not playing

Another thing to check, see if all of the achievements logged same date. It would be slightly tough to log that many in one day so its still possible it just backed up and finally popped

Sometimes they can take a while to pop if the service is having an issue, but years is a bit of a discrepancy that has me worried. Please log into your Microsoft Account page, click "Security" at the top bar and then check Sign-in Activity.

If you see activity that doesn't seem right
IMMEDIATELY follow the steps here.

And look into
two factor authentication for ALL of your accounts.

Usually it can happen when you unlocked it during your last session but did not pop up. So the system was ‘loading’ the unlockment of that achievement. It can happen to have som achievements popping up out of nowhere.

Cool, it's just that much safer. I'd go back to your
Microsoft Account page and click on Devices to see if there is an Xbox on there you don't recognize?

Otherwise is it possible that someone played it on your console?

Well, to be honest, that is normal. If it says it's an unsuccessful log in, then your account is doing what it's supposed to, though you should ENABLE TWO-FACTOR AUTHENTICATION FOR ALL YOUR ACCOUNTS (sorry, I get on a soap box about that, nothing personal).
Those are bad-agents attempting to get into your account and probing Microsoft's systems, I get that list about every two to three days.

What you want to look at are the successful attempts logging in for if that are not where you are.

I'd also look at the achievements that unlocked and see what timestamps they have on them? See if they have a timestamp of years ago when you played, or if they are more recent.