Like all dynamic array formulas, if the source data changes, the results will update.
When you set up a formula that spills results onto the worksheet, you may see a #SPILL error when there isn't enough space for all values.
For example, if I add an "x" to the cell below the spill range, and then change red to purple again, we get a #SPILL error.
However, if I delete the "x", the error disappears and the formula spills properly again.
This can also happen if I overwrite part of an existing spill range.
Finally, notice that the formula inside a spill range is identical in all cells, and the text in the first cell is black, while text in other cells is gray.
You'll sometimes hear this behavior referred to as "one formula, many results". This is a unique feature of dynamic array formulas and a huge simplification that makes it much easier to solve traditional hard problems in Excel.