Hi @bagdonaviciusbm . Welcome to the Shopify Community.
Before this happened did you make any changes to your Locations? If you have multiple locations set up, they could have different stock for each location which would show up differently for customers based on their locations. Try managing your locations inventory and see if that fixes your issue.
If you are still running into this issue after checking you can reach out to our support team who can look into this more for you. Write “advisor” in the chat then follow the prompts to be connected.