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How to deal with toxic coworkers
Highlight their work.
Toxicity is often a sign of insecurity. By giving the co-worker credit or highlighting something that they've done, you may give them some semblance of positivity in their life, which could help with the toxicity.
You may also find a friend you didn't think you could have. For example, tell your boss all that your co-worker has done if you've worked together on a project.