How to stop data in new cells from inheriting formatting from previous rows?

I have a sheet where certain rows / columns have fill colors applied to make things easier to read.

For example: Rows 1-12 (Jan - Dec 2025 ) have a fill color. Rows 13-24 (Jan - Dec 2026) do not have any fill color with the exception of column B, which has the manager's name.

I can highlight the cells in rows 13-24 and set them to have no fill. But when I type a value in any of those cells and tab or enter, the cell inherits the color fill from the section above, even if the row directly above it has no fill.

There is no conditional formatting in use on the cells/rows in question.

I typed 15 in cell F9 and clicked enter, but I do not want this formatting to auto apply.