Hi Andy,
Apologies for the delay.
I did encounter this issue in the past several times.
Here is what I did in Photoshop.
Create a large logo, 1000px width minimum.
Flatten the image, then resize it to a small size (80px).
Doing this has solved the issue for me.
If you like I can also log into your Admin Dashboard and have a look at the SVG logo but I would recommend doing what I explained above.
Hope that helps.