I honestly don’t think those flames were anything to worry about. I have seen a bunch of Falcon 9 landings, and even with those, there are almost always those flames coming from somewhere, lazily licking at the metal.
Those are, I believe, thruster ports, and they have blue focused flames at very high temperature coming out of them when they are being used, so the soft yellow flames couldn’t be anywhere near the temperature the thruster ports are used for.
That’s the way I see it, at least, but...it is true I am no rocket scientist!
:^) Yeah, it seems too complicated to take on. :^)
Manley sez the booster’s just venting as it reaches the tower, around the 12 minute mark:
https://www.youtube.com/watch?v=Ysx4t7ICO58
Videosfromspace has the decel and splashdown, and around the 9 minute mark the giant ball of fire:
https://www.youtube.com/watch?v=Iwaq71P88T8
There is always.going to be flames after landing. Rocket turbo pumps spin at 100,000+ rpm you cannot just turn one off. The spinning mass needs coolant and lubricant both of this functions are provided by the fluid being pumped through it. When you shut down a rocket you flow fuel or lox until the pumps spin down. You vent those over the side while that happens. You see that on every falcon 9 landing as the yellow flames flickering under it. You just saw it on a grand scale when ten raptors of three times the thrust spun down and then three more after the catch. Look up at the vents you can see the vapor coming out before it gets lit up by the running engines or the fact that it just went through a turbine at hundreds if degrees F too. Rewind the video look at the booster right after it stages and all the engines cut off. You see a huge white plumes being vented out the sides...That’s all the turbines spinning down and venting gas to space.