כָּל־עֵצְךָ֖ וּפְרִ֣י אַדְמָתֶ֑ךָ יְיָרֵ֖שׁ הַצְּלָצַֽל׃
All thy trees and the fruit of thy land shall the locust possess.
Shenei Luchot HaBerit
We may simply answer this by saying that all the moon asked for was to retain its size, implying that the size of the sun could be increased. I have explained Deut. 28,43: הגר אשר בקרבך יעלה עליך מעלה מעלה ואתה תרד מטה מטה, "The stranger in your midst will keep rising higher and higher above you, whereas you will sink lower and lower" in a similar vein.