Subscription Downgrade Issue

[kingapex]

We are preparing to launch an application that provides AI models, allowing merchants to place their clothing images on models for display to consumers.
Our pricing plans are as follows:
1. Free: Free, 10 images free
2. Pro: $20 per month, can generate 20 images
3. Advanced: $80 per month, can generate 100 images

In Shopify.dev, we created a subscription plan, but during our testing, we found that users can downgrade their subscribed plans.
This leads to an issue; please consider the following scenario:
1. A user subscribes to the Advanced plan and generates 100 images.
2. The user then downgrades to the Pro plan, which cancels the previous Advanced plan and re-subscribes to the Pro plan.
3. This scenario results in the user actually subscribing to the Pro plan (costing $20) but enjoying the benefits of the Advanced plan.

Can the subscription changes be set to take effect in the next cycle?
Or do you have any better suggestions for the above scenario?
Thank you very much!