Also experiencing this issue, it has been ongoing for some time. I must note that I too see this occur on multiple machines, both at home and at work. It doesn't seem to be limited to File Explorer.
As others have said, in File explorer, the lower frames of the window with the directories and files cannot be clicked on. But you can click on anything from the toolbar and up. By clicking on one of the menus and then tabbing you can still navigate folders. I can still click things like the menu key and open up context menus. If I click anywhere in the lower half of the window, it will lose focus and remain unclickable.
If I open another explorer window while the first one is open, I can click on it without issue. My explorer is currently configured to open each window in the same window.
I know some people mentioned August, but I've been having this problem a lot long er than that.
I tried to use procmon to analyze what was happening, and I noticed explorer reaching out to several entries where ikeeps checking TabletPostureTaskbar and Microsoft.UI.Input.GestureReconizer.
Could the window be going into some sort of tablet mode?
8:41:03.7769856 PM Explorer.EXE 6944 RegOpenKey \REGISTRY\A{5B1D52FB-ADAA-425C-ADA9-10B35C9E2FA4}\ActivatableClassId\Microsoft.UI.Input.GestureRecognizer NAME NOT FOUND Desired Access: Read
8:41:03.7770199 PM Explorer.EXE 6944 RegCloseKey \REGISTRY\A{5B1D52FB-ADAA-425C-ADA9-10B35C9E2FA4}\ActivatableClassId SUCCESS
8:41:03.7770645 PM Explorer.EXE 6944 RegOpenKey \REGISTRY\A{7AC32957-BD48-4D57-9D8D-19C6053130CE}\ActivatableClassId SUCCESS Desired Access: Read
8:41:06.9674576 PM Explorer.EXE 6944 RegOpenKey HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer SUCCESS Desired Access: Query Value
8:41:06.9674996 PM Explorer.EXE 6944 RegQueryValue HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\TabletPostureTaskbar NAME NOT FOUND Length: 16
8:41:06.9675336 PM Explorer.EXE 6944 RegCloseKey HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer SUCCESS
8:41:06.9675777 PM Explorer.EXE 6944 RegQueryKey HKCU SUCCESS Query: HandleTags, HandleTags: 0x0