Old solution from here seems work with new Edge version.

Googled.

GDIProcessHandleQuota - was found here and seems it's my case:369829
Some details about it.

MultiTaskingAltTabFilter - controls Alt+Tab behavior in Settings->System->Multitasking
...

Hi,
Don't know what exactly, but these settings solved issue for me:

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
"MultiTaskingAltTabFilter"=dword:00000003...