The best solutions so far gave Blue either 2 units of territory with Blue having the first move elsewhere, or 3 units of territory with Red having the first move. This solution is 3 units for Blue in sente, with the option for 4 more units locally (if that’s the best move available).
Here when Red plays 1, Blue responds by taking 3 units immediately with 2. This also limits Red to only one solution to taking territory, so Red 3 for just 1 unit is required if Red is to live inside.
At that point Blue can play elsewhere if something of more value is available, or play at A for 4 more units, so all around this is a much better solution for Blue.