React CSS sourcemaps point to missing source files

I’m getting this warning in console:

Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/normalize.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/core.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/structure.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/typography.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/float-elements.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/padding.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/text-alignment.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/text-transformation.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/flex-utils.css" points to missing source files
Sourcemap for "/Users/me/my-project/node_modules/@ionic/react/css/display.css" points to missing source files

Both the css files and the maps are there:

I’m not sure what the maps should be pointing to, but indeed in the map (ex: normalize.css.map) it is pointing to some src file, rather than the files in the package:

{"version":3,"sourceRoot":"","sources":["../src/css/normalize.scss"] ... more

This is a known issue with react-scripts@5.