Same issue here, i was able to "solve it" by downloading the simulator for ios 15.2 instead of 15.4, then creating a new simulator using that version.
Now the simulator loads, but only on devices with 15.2 .
Just open xcode -> windows -> devices and simulators, click on the Simulators tab , click New, click on the OS Version dropdown and choose "Download more simulator runtimes", download 15.2 and create a new simulator with 15.2 as OS Version.
There seems to have been a problem with the simulator runtime for 15.4 in this xcode version