AIO Coworker making props to mock me at work, is this harassment?

I work as a fitter for an office fit-out company (building desks, chairs, tables, etc.). I’ve been here 4 months and am still in probation.

One coworker has been negative since day one by badmouthing the job, the pay, and everyone else. He talks down to people and makes them feel incompetent.

On Monday, he told me he’d “heard” I was getting fired soon because I’m “too slow” and once damaged a table. He said he was “doing me a favour” by letting me know so I could find another job. I suspect he’s been talking about me to management.

The next day, he made a fake “trophy”/magic wand with a sign saying “budget friendly staff replacement device”, showed it to everyone in our department, and laughed. Pretty sure it was aimed at me. I honestly couldn’t believe he would spend enough time out of work to make something like that in order to mock someone else who works in the company. Is this normal behaviour or are my feelings justified.

I’m angry and uncomfortable. I haven’t said anything yet. Is this harassment? Should I take it to management/HR or just keep quiet until I leave?