In a moral sense, you shouldn't need to. Your English is functional enough to work with. It's not your fault if people make poor judgements about your ability based on your English skills.
Unfortunately, we can't expect all the people we work with to overcome their prejudices, so it's probably still useful for you to improve your English skills.
Unfortunately, we can't expect all the people we work with to overcome their prejudices, so it's probably still useful for you to improve your English skills.