When I buy an item, my dynamic price provider changes the price but item has still old value in his lore. So when I click once more, I pay different price than displayed. The price is also not updated in category inventory.

Spigot version: 1.16.5
Plugin version: 8.5

For testing purposes, having the plugin you use could really help with this as I never finished implementing and testing my own DynamicPriceProvider. That would save us some time attempting to recreate the same environment.

I tested this with older version of GUIShop (with my changes included) and it was working. The only case where problem appeared was when player A bought an item and player B had open shop at that time - the price did not update obviously for player B.
In zip I included an example image of how price should change over time. Exact numbers depends on buy/sell price set in config (it is calculated from them).
I don't have much time testing this for newer version, but this dynamic price addon should remain the same because interface does not change.
guishopaddon.zip

I will look into this and see if I can find the issue. Would you mind adding me on Discord? I may need the plugin you are working on to find the exact cause of the issue.

Discord: Bryce# 0001

Perhaps @A248 can look into this when he has time?