how to create storage RLS policies

filePathexample: public/{User UID}/{random UID}.jpeg

const { data: uploadData, error: uploadError } = await supabase.storage
        .from("avatars") 
        .upload(filePath, avatar, {
          cacheControl: "3600",
          upsert: true
        });

Upload error: {
  statusCode: '403',
  error: 'Unauthorized',
  message: 'new row violates row-level security policy'
}