Earth’s axis is tilted to one side. Which phenomenon would cease to exist in the absence of this axial tilt?

The Earth rotation axis is inclined (or tilted) approximately 23.5º with respect to the plane of the orbit that it describes around the Sun.

If this inclination did not exist and the axis of the Earth were exactly perpendicular to the plane of its orbit around the Sun, day and night would always last twelve hours and every day of the year would be a perfect repetition of the previous one.

Therefore, the solstices (maximum difference in duration between day and night) or seasons would not exist.

this would start to sound a little like mortal combat