Potential employer says they’ll put me on part-time once maternity leave employee returns. Should I take the job?

Greetings!

I had applied for a full time job recently and was selected for an interview, everything went well, and they called me in for a trial shift (paid). Well after the shift, the employer told me that a previous employee was on maternity leave, and was supposed to return much later but they’re returning sooner. Due to that they will be putting me on a part-time schedule after 2 months of employment, and back to full time employment once the season picks up October onwards. This was all verbal. I agreed to it in the moment but now I’m having doubts. During the interview they emphasized how they’re looking for someone who doesn’t dip and stays long term.

Should I take the job? I’m currently working 2 part time jobs and I’ll have to leave both for this job. This new job is better than my current jobs and I’ll get to learn a lot. But I doubt a 2 month experience would add any value to any future employer.

I have a feeling they’re only filling in a temporary empty spot under the guise of full time employment to get more candidates. And they’ll give me the boot once the old employee returns. But then why would they keep emphasizing how they’re looking for a long term employee?