diff -rauN hugo-0.120.1/hugolib/site.go hugo-0.120.1-charset-patch/hugolib/site.go
--- hugo-0.120.1/hugolib/site.go	2023-10-30 17:44:31.000000000 +0100
+++ hugo-0.120.1-charset-patch/hugolib/site.go	2023-12-12 18:12:53.960153106 +0100
@@ -400,7 +400,7 @@
 func (s *Site) RegisterMediaTypes() {
 	for _, mt := range s.conf.MediaTypes.Config {
 		for _, suffix := range mt.Suffixes() {
-			_ = mime.AddExtensionType(mt.Delimiter+suffix, mt.Type+"; charset=utf-8")
+			_ = mime.AddExtensionType(mt.Delimiter+suffix, mt.Type)
 		}
 	}
 }