Minecraft Skins and Purchases Transferring to Another, Separate Account Automatically

Hello, I've tried scouring the internet for a similar issue to the one I've been having, but for the life of me I've been unsuccessful in finding ANY help. So, here's the situation:

I own Minecraft on Xbox, and my brother owns it for Windows 10. Occasionally, we will play on the other's platform (I'll log into my account on PC, he'll log into his account on Xbox) in certain instances, like when one of us wants to play PvP on Hive, for
example, that person will play on PC. That's besides the point...

Before the recent issues with Realms and Minecraft accounts (Week of 1/10/21), we NEVER had any issues with account syncing between platforms. When I logged into PC, I had access to all of my previously purchased content and the content I receive for paying
for Realms Plus, and when my brother logged onto Xbox, his content was available to him. However, starting some time last week, ALL of my previously purchased skin packs and ALL access to Realms Plus content disappeared from my account. No matter where I signed
in, or what troubleshooting I did, it was as if all of my content vanished despite me still paying for Realms Plus and being able to track down my purchase history (dating back to May of 2012).

Lo and behold, when my brother logged back into his account on the PC for the first time since Realms began experiencing issues, my Minecoins and ALL of my previously purchased Skin Packs appeared on HIS account. Again, I tried signing out of and signing
into both accounts, using the "Save to Microsoft" and "Leave On Device" options in reference to purchased content when signing in, and essentially every other standard piece of troubleshooting, and yet I have found ZERO ways of getting my content back on MY
profile. And the most confusing aspect of this all is that I don't have any access to his
content - that's all on his profile, so it's not as if our accounts completely switched - it's only my stuff that appears on his account. My guess is, somehow, my profile synced as if it were his, or his synced as if it were mine, when launching
the game before/during the period in which Minecraft was experiencing difficulties, but that's just speculation -- I genuinely do not know how this happened.

I've spent a good while trying to find solutions on these forums and elsewhere online, but I have yet to find this issue replicated anywhere, so I've come here for help. I can't think of anything that would cause this glitch, or bug, or whatever to happen.
Like I said, we have NEVER had an issue with signing into our accounts on each other's platforms/Xboxes, and yet now Minecraft is acting as if MY account is his, complete with MY purchases and MY Realms Plus access. Can anyone please help shed some light on
this and provide me with help?

:)