Wrong place to ask, you should ask Microsoft that. But likely it would be a loss of those games.

If the game was redeemed on Steam, it will stay in Steam. If the game requires a Microsoft account to play, all data associated with the previous account will be deleted.

Just like other third-party accounts, all data within the account will be deleted though Microsoft allows you to create a fresh one and link it through the same Steam account unlike other publishers (should you missed an unlink option before deleting).

ok

I just tested this out but I didn't close my old Microsoft account yet and I was planning on creating a new email address anyways, an Outlook one specifically. For some reason my copy of FS2024 (Steam version) won't work with my new MIcrosoft account as it gives me a message about the wrong XBox Network Account for Steam FS2024 and to switch to the correct one. I originally played it linked to my old Microsoft Account. All my other Steam version of MIcrosoft Games work with my new Microsoft account, including the Steam version of FS2020. My Steam version of FS2024 will only work under my old Microsoft account which is not how I want it. Also now FS2024 (Steam version) is locked to my old XBox profile and there is no way to logout of it inside the game. I was planning on closing my old Microsoft account and email address. This seems like a hit and miss, or should all my Steam version of Microsoft games work under my new Microsoft account or is it just specific games that will? Shouldn't all my Steam version of Microsoft games still work under my new MIcrosoft account since I purchased those games through Steam, and not MIcrosft (for the Steam version of those games)?

I got it all resolved through Microsoft's Flight Simulator's Zendesk tech support.