I just solved this is a surprising way
Here's what happened.
I've been using Lucky Patcher with Multi Patch to remove licence verification, Google ads, and redirect in-app purchases to Lucky Patcher. However, the store kept showing "Retry" instead of the normal prices.
Today, I was bored and randomly opened Lucky Patcher, clicked on the game, went into Tools, and stumbled upon something called Purchases Sorter.
Out of curiosity, I opened it, and it showed all the available purchases in the game. There were options for In-app and Subscription, with checkboxes beside each purchase.
For some reason, ALL of them were checked as Subscription.

My brain, operating on absolutely zero technical knowledge at that particular moment, suddenly asked: "What would happen if I changed all of them to In-app instead?"
So I did.
I launched the game and prices actually appeared


Unfortunately, clicking on them still didn't work. I was disappointed, but then I thought, "Hmm, let me close the game completely and try again."
I reopened it, clicked on the 1,000-coin pack, and 1,000 COINS ACQUIRED!
Kept doing it till 10,000. Then purchased the other packs with the coins. This is what worked for me. Don't know if it'll work the same for you. GOOD LUCK.