The text on the left is from the originating PDF file, the text on the right is overlayed dynamic data passed into the tab.
The original PDF looks rasterized (likely) is there a way to optimize rasterization to avoid this? I don't see any parameters/mention in the API docs.
I'm a HelloSign API support engineer and happy to help!
When you create the signature request, we do some processing of the document on our servers then present this doc to the signer, and when they've signed we also do some final overlay work with their signature. Unfortunately there's no optimization you can do, we just recommend using PDFs over any other file type as those come out best.