It was great to see that they seemed unconcerned about 3 engines not lighting on launch. That's the sort of redundancy Starship is going to need to succeed in the way SpaceX are aiming for.
For roughly 10 seconds the telemetry reported 5 failed engines, then the last engine to fail re-ignited. But from the photos it looks like a total of 6 engines were off for longer period of time, 5 at the outer rim and 1 of the inner 3.
Thats 6 of 33 engines out, or 18.18%. Incredible it was still accelerating upwards