It's a know issue that if you choose Custom Logo Design option and upload a logo, sometimes it appears too small or blurred. In most cases, it's resolved by following the steps given below:
Check the resolution of the image that you've uploaded as logo
If it's too large, scale down the resolution of the image
Re-upload this updated image and see if the logo appears better
If you still face any issues or have any concerns, you can reach out at [email protected]