So was at dog park today (one where dogs can run off lead). A puppy (but large breed so larger than my dog) jumped on mine - first time mine growled, second time, growled again - third time really did “react” didn’t bite or anything like that - but certainly barked and showed teeth.
I did put him on lead after second growl but the other owner just left her dog to jump on mine. I left the park - but am I unreasonable to think she should have put hers I lead. Two other dog owners left the park while the dog was running around.