Hi Bruce. I am running Full AutoCAD (not AutoCAD LT, not Mechanical, not Electrical, not any of the rest) and I did not install until the 2022.0.1 update was released. I just checked the ReadMe for the update but no mention was made regarding SYSFLOATING. However, they may have snuck something in there that fixed the issue, so check to see if you have installed the update yet. If you have done so AutoCAD will show the product version as 2022.0.1 when you look at the Help>About AutoCAD 2022 pull down menu.
Otherwise the only way I can duplicate your installation's behavior is to set SYSFLOATING to -1, then I can't drag the tabs to open desktop space. If I set SYSFLOATING to 1 it immediately performs a downsize window and shows the drawing in the same place on screen but with the drawing name and path in the downsized window instead of in the AutoCAD window, and it is sitting right in place where my other drawing is open in the full AutoCAD window. If I click into the floating window and change SYSFLOATING to 0, it immediately nests back into the full AutoCAD window right alongside the other drawing tabs.
The only other thing that comes to mind would be related to docking stations if you use a laptop and extra monitors. The driver updates on many docking stations cause some unexpected behavior with various applications.
So check the update if you have not loaded it and see if that helps and maybe try this using only one monitor too.
HTH,
ADN CAD Developer/Operator