maggie, I want to second what greg said below. This is the second thread we are seeing where this %PUBLIC_URL% is causing problems - unfortunately, this is something to do with the tool you are using to build the site, and not Netlify, I dont think.
Here is the other thread:
In the readme, here: GitHub - maggieprice/portfolio-main it says:
Only files inside the public folder will be accessible by %PUBLIC_URL% prefix. If you need to use a file from src or node_modules, you’ll have to copy it there to explicitly specify your intention to make this file a part of the build.
When you run npm run build, Create React App will substitute %PUBLIC_URL% with a correct absolute path so your project works even if you use client-side routing or host it at a non-root URL.
In JavaScript code, you can use process.env.PUBLIC_URL for similar purposes:
can you tell us the build setting you are using to run things as part of your build step (your build settings)? It seems like CRA (create react app) isn’t substituting the URL the way it is supposed to.