We had internal test with alpha / dev, but those tests can only do so much. You can't beat users when it come to find errors or breaking things.
Some have a 5 year old windows installation with a lot of conflicting software, disabled windows features that are not really meant to be disabled, have unstable memory, changed cpu / gpu brand without reinstalling, have torrent / crypto miners (without always knowing it's installed), virus, cracked games, forced unsigned / modified driver or bios or firmware, you name it.
But EAC is not new, and it's already running on other projects