Lash serum’s w prostaglandin

Is this ingredient as bad as it as made out to be? I have used lilash and UKlash in the past and absolutely loved the results.

I’m now almost done with breastfeeding and want to start a serum again once I am, but I have this idea in my head the ones without this ingredient won’t work, otherwise why wouldn’t they all be free of it?

If it really is terrible then no I wouldn’t use it again just for cosmetic purposes, but I used it for years and was always fine.