Unity2D vector sprite sheet is blurry compared to single image with the same resolution.

Here I have two images. The first one is a sprite cut in Unity form a sprite sheet with the dimensions of 14837 x 10502. The second one is the same vector image but it is imported in Unity as a single image with the dimensions of 1719 x 730. They have the same quality, I copy-pasted the image in Illustrator from the sprite sheet and exported it alone. How can I fix this? It took me 2 days to take all the UI and add it in a one image just for the sake of batches and performance since it will be a mobile game. Increasing the resolution of the sprite sheet doesn't really help. Do I need to change the pixels per unit? I never really understood how to use it. Thanks.