At least one engine looked faulty from the start. It left a light smoke trail and the exhaust was glowing yellow. That is unusual for a methane engine and might point to a fuel rich propellant mix. This could lead to excess carbon in the exhaust, which will emit yellow light, instead of the expected blue light.
Second indicator was the small green flame that erupted during relight. Green flame in this case looks like burnt up copper, again pointing towards an unbalanced fuel mix, which could explain the loss of thrust shortly before touchdown.
A similar thing happened during the launch of SN-8: SpaceX's Biggest Starship Flight Is A Spectacular Success Even After Crash Landing.
It might be that the upgraded header configuration after the SN-8 failure is capable of supplying a two engine relight, but not a three engine restart - which was implemented after the failed flip of SN-9.
Launch and Landing
Starship SN-10 had a successful test flight, but exploded some time after a rough landing on the pad.
SpaceX livestream replay: Starship | SN10 | High-Altitude Flight Test
Scott Manley with a detailed photo study of what went wrong. Including the bounce on landing and wobbly legs shortly before touch down.: SpaceX's Starship SN10 Successfully Lands After Amazing Flight. Dismantles Itself Spectacularly
Tim Dodd with insane high quality slow motion footage from his new studio in Boca Chica: Starship SN10 [4k, Clean Audio & Slow Mo Supercut]
NASASpaceflight compilation of different amazing camera angles: Starship SN10 10km Test Flight, Landing, and Explosion
NASASpaceflight: SpaceX Boca Chica: Starship SN10's Wreckage Cleaned Up
Tim Dodd at the impact zone, looking at bent metal: Checking out the Starship SN10 wreckage!
Preparations for SN-11 are already under way. Expect another attempt soon. Let's hope they already have better legs ready, because the current iteration seems woefully unprepared to save the rocket for a second flight. Thruster reignition and thrust modulation above the landing pad seem fairly straight forward fixes at this point (for SpaceX ;) ).
NASASpaceflight: SpaceX Boca Chica: Starship SN11 Rollout Preparations are in Place
Update: they don't stop.
Background information about previous SpaceX launches: Wikipedia
Useful links to stay up to date on launches:
Spaceflightnow.com: Launch Schedule
Everyday Astronaut: Prelaunch Previews
NASA Spaceflight nasaspacefight.com