We are also still having the same issue - it is now Mar 2025, and still no solution from Shopify. Attempting to correct the issue of the default error modal that is triggered when adding a quantity of items above the available stock when using any Stepper UI components (with the modal having its own bug by redirecting and emptying the cart when Customer clicks ‘Continue Checkout’). We are having to build a Proxy Admin API to get inventoryData in our Checkout Extension just to prevent this bad experience.
Upon reaching out to Shopify about this issue weeks ago, they informed me this is a known issue and they did not have a timeline for when this would be fixed. My ticket was taken out of the active queue. In case any of you needed to know their priorities at this time.