I also play on xbox. This has also happened to me. In addition to the CP differences, it completely reset my CP on one of the affected characters. It has also caused bank inventory items to appear in characters inventory, enough to fill their inventory to max. There are other issues as well including missing gold, login rewards, and hirelings. After 2 days of talking with support they finally (after telling me first i was hacked, the it was supposedly a connectivity issue on my end) they realized my issues were tied to syncing issue they released a small statement about a few days ago on the website. After we came to the part of the different CP amounts is when they determined i was included in the issue. A guild mate also has this same issue. I was advised not to play on the affected characters until its fixed. Which it seems to be 7 of 8 characters.

It sounds like you are effected by the same thing many other folks are dealing with.

https://forums.elderscrollsonline.com/en/discussion/599225/account-reset-to-about-2-weeks-ago

Here is the lowdown on what I have encountered: My main character that I play daily was CP 252 when I logged off Monday night February 28, 2022. The next morning though, Tuesday March 1, 2022, when I logged in to begin playing again I noticed my level had been reset back to CP 141. Meaning I had lost the last 111 levels of CP that I had worked the last couple of weeks accumulating, along with all the money and others things that go with multiple weeks worth of daily playing erased. Something else I am noticing while is that if I perform any action like claiming the daily reward, advancing my daily riding level, using an experience scroll, claiming my daily resources from mail deliveries, that after I log out and then back in they system does not register that I have performed any of those events and I can do them again, and again and again as they are never registered as being done. Also keep in mind that this is just the loss on my main character, I have 6 other characters that I have not went into detail about but I do not play them daily but I did notice that they all had their CP points set back to only 141 instead of the 252 they should have access to since my main and highest level character is CP 252.

And here is the response I received from ZOS for the ticket that I submitted:
_________________________________________________________________________________________________________________________
Greetings!

Thank you for contacting The Elder Scrolls Online Team.
We are aware of an issue where the progress for some characters has been reverted. We are working to fix this issue as soon as possible. In the meantime, we advise that you do not continue to play on the affected characters. Any new progress made before the issue is resolved may be lost. Once we have an update, we will be sure to reach back out to you.

We appreciate your patience while we work to sort this out.

Thank you,
The Elder Scrolls Online Team
_________________________________________________________________________________________________________________________

That was early yesterday March 2 and I have heard had no additional updates since.

Agreed. Both myself and my wife play, but she plays considerably more than I do. Since she is disabled, it is something that she throws herself into to keep herself occupied - i.e. housing, officer in a guild, etc.. Without it, it is a bit distressing for her. Hoping for all impacted parties, that it is resolved as soon as humanly possible!

Thank you, again, for pointing me in the right direction on where to find information on this!