i have also this issue. Last time i could play normal it was on tuesday evening.
On wednesday i coudl start sc2, but then it freezes. I cannot logout of sc2, or switch to my normal windows desktop.
I can reboot or logoff to windows. And then logon again, but not use sc2.
i tried some old idea’s but it did not work: Starcraft 2 startup suddenly slow
I guess its because of an update of the battlenet launcher.