App I bought a couple years ago asking me to pay for it again

I bought an app in August 2020 and I’m trying to download it again and it wants me to pay. I’m using the same device and same account I originally bought it on and I found the invoice in my email and in my purchase history so I know I definitely bought it. I’m pretty sure I never asked for a refund or anything either. Why is it asking me to pay again and what can I do about this?