PU coat on top of oil + beeswax

Hey all! Redid my wooden countertops with linseed oil plus beeswax. Total beginner here so got tips from a friend. While the result looks and feels amazing, and seems to keep water out just fine, I already have a big round watermark from a pot after only a week.

We cook for a lot of people quite a lot and I guess a semi wet pot got left on the countertop.

Now this stressed me out quite a bit as I thought the finish I did would keep stuff out a lot better. Of course some damage accumulates but to be honest I'm quite upset with this result.

So now looking into a PU finish. Multiple layers.

My question: can this be applied on top of my current finish? (Planning to do multiple layers) or do I need to sand it all down again ?

Thanks in advance !!