Google SERPs sometimes showing the difference between the original price and the sale price, instead of just the sale price

Hi, I work for a retail site and we're having a weird problem, where Google sometimes displays the reduction in price, in the SERPs, as the full price of the product, instead of the sale price. e.g. a product was £50 and is now £35, Google might display £15.00 Weirdly though, my colleague sees some with this problem that are working fine on my side. So I don't know if it's just a weird sort of AI glitch or something, since the reduction isn't even recorded in a field etc. I've checked Google Merchant Centre and the prices look fine there, original and sale prices recorded. The schema also looks correct, the sale price is in the price field, with an offer recorded and the date that the offer ends. So I'm just wondering if anyone has the same problem and might have fixed it, or do you have any ideas? Thanks