When the Fiddler Certificate Inspector extension is loaded github.com/vcsjones/FiddlerCert/ and running Fiddler in a Hi-DPI screen, the rendering of Fiddler looks particular hard to read as *all* of Fiddler has incorrect DPI.
I am the author of Fiddler Cert and I'm not sure why Fiddler Cert Inspector is causing the rest of Fiddler's DPI to appear incorrect.
Using the --dpi-aware flag when starting Fiddler fixes the issue.