It has 33 in total on the booster. It appears that 1 or 2 failed to light, but the booster has multi engine out capability throughout the course of the flight. The internet rocket scientists suggest that both of the hydraulic loops died in flight, you can see it burning off in the exhaust plume. This booster was rhe last one to have hydraulic thrust vector control so it appears it lost engine gimbal capability, thus the cartwheels it did before RUD. Next booster to fly has electric thrust vector control, so won't be an issue. The next booster should also be able to fly the duration even with 7 engines out provided no other issues.

It's the shape of a Q as seen by the red outline.