There's a new feature that was added to the Doximity Fax feature for website users regarding image quality.
When sending an image/document in a fax, click on the 'Toggle' button located to the right of 'Contains Images' on the bottom of the display to enable this feature.
When you enable this feature, it will retain the image quality.
Please note: this feature will have to be turned on each time you send a fax that contains images, as it is not automatically enabled.