The tabs are fine. Tabs in "cmd" are also good.

The window handles, on the other hand .. this was correct in Windows 3.0 and there's basically no good reason to have changed it. There should be a title bar. Active window should have visibly contrasting title bar. There should be sufficient grab space all round a window to get hold of it.

Bonus points: move your mouse pointer very slowly around a bottom curved corner window handle on Windows 11. Ask yourself: how well does "place I am pointing at" line up with "where the curve is"?

Oh man. the complete lack of definition or contrast from window to window is terrible. Which window are you clicking on? Nobody knows. It's especially painful when you have like three or four nested RDP sessions going on.