Meh. I see where they were trying to tie it with the garage gable end vent, but the rounds look out of place on that home to my eye.

Remove it. I would change out the vent too, to a rectangle.

Yep vent would need work too!

Do you have spare siding so you can patch it if you remove the half round window? If the siding has been up for a while it might not be the same color anymore as new pieces. If you aren't able to do a seamless patch job, leave it alone. If it's time to replace the siding anyway, remove it. It is a dated feature, but since you only have one it's not a big deal. I am not a fan of the triple casement window look, so when you're looking at replacements, consider doing something else like a double to match the other window on the front of the house.

Add a wall pergola over the garage door. Decide if the arched window should be changed to rectangular.

I agree do a taller window or at least the transom and the arch vent in the garage can easily be changed

The arched window is very 80’s so if you are trying to update and the window has to be replaced regardless..