Seems like none of these major websites detected anything, and they are supposed to be top-notch in the world.

It's only because the researcher contacted them.

Also because nobody actively exploited them! You're using the word "detected" to mean "discovered", which nobody working in the field would ever do.

	▲	rvnx 13 hours ago \| parent [-]
		detected: WAF caught or detected the attack and raised an alert, post-exploitation discovered: they audited or pentested themself and found out, preemptively I just mean that Coinbase didn’t see anything happening and didn’t take action though the boy successfully exploited the vulnerability on their live system.