Power Pages Licensing Question

Hello,

I did some additional research and was able to find out part of the answer to my question. Prior to 2020, the Portal was included if you purchased 10 licenses of D365 Enterprise and there was no need to purchase additional users. That changed in 2020 to the current model that has a monthly fee based on the number of users. Existing customers were grandfathered in. We have a client that was grandfathered into the old licensing model. They received a notification for the first time this month that they were over capacity on users for the month of January. This is new and they were never required to purchase user licenses for the portal previously. In December they switched from an annual to a monthly SKU of D365. My new question is, did changing the SKU make it so Microsoft no longer recognizes that they were grandfathered in, or did the grandfathering period end in December 2023? If this is not something you would know, do you have a resource you could direct me to?

Thanks!