The first image is the boost phase of the STP-2 telemetry, with what looks like a single side booster engine shutdown event.

Some computed values for the STP-2 launch:Center core cutoff at 11083 km/hr ( = 3079 m/s) at altitude of 123 km and time 3:34. Staging speed is therefore 99 m/s more then Arabsat 6, which was 2980 m/s. Re-entry burn starts at 9:43, so coast was 6:10 or 370 seconds.Assuming re-entry burn at 60 km, we can solve for vertical component of velocity by solving 123,000 + v*t - 9.8/2*t^2 = 60,000, where t = 370 seconds. We find a vertical velocity at cutoff of 1643 m/s. Given the overall speed of 3079 m/s, horizontal speed is 2604 m/s. Coasting at this speed, in 370 seconds the stage covers 963 km, so all is consistent. (The rest is launch to sep, and entry to landing).Peak altitude is 261 km at 167.5 seconds after staging. The energy per kg that must be lost by the stage in landing is g*h + 1/2*v^2, and is 5,946,000 joules/kg. For comparison, Arabsat (103 km, 2970 m/s) was 5,449,000 joules/kg. So this landing was 9% more energetic. More significant, most likely, are (a) less fuel left for slowing down, as more was used for boost, and (b) a steeper angle of re-entry from the much more lofted trajectory.

All satellites are on orbit and have made contact! 🛰👏👏👏 #STP2 #SpaceStartsHere #SMC #SummerofLaunch19

First few shots: Last night's Falcon Heavy launch of STP-2 carrying 24 sats for the US Air Force, NASA and others. This view shows the interaction of the first stage exhaust plume with the two side boosters after they separated and began their engine burns to return to the Cape.

Falcons landing

If we were to save more Delta V for the centre core landing, would the second stage have spare Delta V enough to complete the STP-2 mission? Cause then the core wouldn't have crash landed......I guess

Yes, but we couldn’t take a chance on 2nd stage failing it’s 4th maneuver. This mission was more complex than anything I’m aware of in history of rockets. RIP center core, you did your duty well.