i get this question from junior designers a lot. i didn't make this switch myself but i've watched several colleagues do it and i've had enough coffee chats with PMs to have a real opinion. here it is.
what you already have as a designer switching to PM. user empathy. you've done research, you've synthesized user feedback into decisions, you understand what a good experience is. this is genuinely valuable and a lot of PMs don't have it in any rigorous form. you probably also have stakeholder communication skills from presenting design decisions. these transfer.
what you don't have, and where designers overestimate themselves. the business/data fluency gap is real. most PM interview loops include a metrics question (something like 'your feature launched, how do you evaluate if it worked') and the answer they want is more specific than 'i'd look at engagement.' you need to be able to say: here are the 2-3 metrics i'd pick, here's what i'm trying to isolate, here's how i'd avoid being fooled by the obvious metric. if you can't do this well you'll fail the PM loop at most mid-to-large companies.
the other thing: PM roles expect you to own roadmap and prioritization decisions with partial information and cross-functional pushback. designers are often insulated from the upstream business pressure that shapes product decisions. you might find you don't actually love being in that seat. spend time with a PM in your company before making this move if you can.
what the interview loop looks like. most PM loops have: a product sense round (design a product for X), a metrics/analytical round, an execution/estimation round, and behavioral. your design background helps most in product sense but the other rounds are hard regardless.
leveling. you'll almost certainly start at APM or PM level even with several years of design experience. one of my colleagues with 5 years of design experience started as an APM at a B2B company. that's pretty typical. the trade-off can be worth it depending on your trajectory goals but go in with eyes open.