try

Author: dimaMachina

packages/plugin/__tests__/mocks/import-fragments/valid-baz-query.gql

@@ -1,6 +1,6 @@
 # Imports could have extra whitespace and double/single quotes
 
-#  import  BazFields  from  ".\other-path\baz-fragment.gql"
+#  import  BazFields  from  "./other-path/baz-fragment.gql"
 
 query {
   baz {

packages/plugin/src/rules/require-import-fragment/index.ts

@@ -89,12 +89,7 @@ export const rule: GraphQLESLintRule = {
 
           const extractedImportPath = comment.value.match(/(["'])((?:\1|.)*?)\1/)?.[2];
           if (!extractedImportPath) continue;
-
-          const importPath = path.join(
-            path.dirname(filePath),
-            extractedImportPath.replaceAll(/[/\\]/g, path.sep),
-          );
-
+          const importPath = path.join(filePath, '..', extractedImportPath);
           const hasInSiblings = fragmentsFromSiblings.some(
             source => source.filePath === importPath,
           );