I missed the part about why they were using 3 engines for the re-entry this time?
Mass of payload and type of orbit left VERY LITTLE fuel to try to land. They did have a reentry burn, always use 3 engines for that (1-3-1 sequence). For landing, they normally land using one engine. And it takes about 30 seconds to slow down on that one engine, to near zero velocity at landing. All that time, there are gravity losses:
https://en.wikipedia.org/wiki/Gravity_drag
So with remaining fuel too low to make a normal 1 engine landing, to reduce the gravity losses, they ignite three engines for most of the landing, so rather than fight gravity for 30 seconds, they fight it for.... around 15 seconds (? Maybe 10 seconds with 3 burning, 1 and then later 4 seconds with center only). Let's say 15 seconds, so half the gravity losses.
So, imagine if the Falcon booster could hove in place, which is 1G. The fuel that it would take to hover for 15 seconds, they saved that much fuel with the 3-engine landing (If the landing burn was shortened from 30 seconds to 15). But it is also riskier, which may be a factor in why it was more over the water than over the ASDS deck when the exhaust blast started to touch the surface.
This is perhaps the 5th time they have done this. One time, it ran out of Lox before touchdown and hit hard enough to damage the Falcon to cause it to leak RP-1 and catch fire, then fell over from fire damage. The other times the booster landed safely, but IIRC none of those have been slated for a re-flight, as they had a lot of heat damage. Unknown publicly whether the heat damage was severe enough to make them unflyable, or just extra-expensive and needing more time to repair/refurbish. Also unknown if the engines themselves suffered from heat damage, or if those are OK to swap to another booster for re-use (the engines cost a LOT).
Block 5 Falcon, to start flying near the end of the year, is going to have some upgrades to make refurbishment easier, as well as better heat protection. And bigger grid fins which can allow for a more lifting body-type glide re-entry, at a shallower angle (more horizontal than vertical), which would cause less peak heating than the current re-entries do. As it is, the existing grid fins make it "glide" a bit, but only enough to alter the descent path some, not big enough to do the kind of shallow lifting re-entry they need.
BTW - there were rumors that "Roomba" might be used after landing. But no onfo yet on whether it's being used. Roomba is the nickname of the big wide robot to be used to help secure the Falcon on deck rather than human crew needing to attach the Falcon to the deck by installing jackstands, welding steel anchors to the deck plate, and attaching/securing chains to the Falcon to hold it for the trip back to port.