Noticed that the renders look a bit fuzzy on 1.16 compared to 1.15, I am using the same option for the quality of the render.

Dynmap 1.16

Dynmap 1.15

I suspect this is due to the default now being jpg rather than png.

Can you do a compare of an old configuration.txt file and your current file?

Default is JPG vs PNG - if you want PNG, just switch back and rerender.