Ullage

Animated Starship Plumbing Diagram
C-bass Productions
Here's my contribution to the celebration of SpaceX getting the nose cone mounted on Starship SN8. This is another animated video about SpaceX's Starship prototype. The last one was made by C-bass Productions as well. This one shows how fuel is distributed and consumed during a flight. 

The dedicated tanks for landing is new to me, but it makes good sense. Watching it for the second time though, that LOX tank in the nose is making me nervous. I don't suppose it makes much difference where it is, if anything goes wrong anywhere in the ship, it will all be over in a flash.

Here are a couple of my posts with Scott Manley videos:

• This one talks about the oxygen tanks and relighting an engine in zero gravity.
• This one talks about the landing procedure.

Looking around, I found a couple of comments about these dedicated fuel tanks, also called header tanks:

Those are the header tanks that contain the landing propellant. They are separate in order to have greater insulation and minimize boil-off, avoid sloshing on entry and not have to press up the whole main tank. - Elon Musk

Now, the new reason for the Starship header tank is that by putting it in the very tip of the nose of the Starship you move the center of mass higher on the rocket - especially during reentry. If the fuel was in the main tank, the weight and balance would be too far aft for the 'skydiver' horizontal return method. So putting a separate tank in the nose of the Starship solves a whole lot of problems at once. - StackExchange

Lastly, we need to consider ullage:

In the weightless condition in space without engine thrust, empty space occurs in partially filled tanks, and the liquid floats away from the engine intake, which is undesirable for stable engine operation. Small rocket engines are sometimes used to provide enough acceleration to settle the propellant to the bottom of the tanks prior to ignition of the main engine(s). Engines devoted to this purpose are called ullage motors; sometimes reaction control system thrusters are used. - Wikipedia

Ullage motors do not need to be very powerful, pressurized nitrogen gas could be used. No need for a full fledged rocket motor burning fuel and oxygen, a simple nozzle with a valve is all that is needed.