
I believe AI Builder requires its own license, irrespective of any licensing for use of premium connectors.
I think most (all?) AI Builder components require you to have Dataverse (in my cynical way, I suspect that is an entirely artificial requirement, but a requirement it is never the less).
So, my understanding is that you will need either D365 or Premium licenses per user per month to get Dataverse and then you will need an organisational AI Builder license to use the components.
AI Builder Licensing - AI Builder | Microsoft Docs
AI Builder is just the Azure Cognitive Services wrapped into components that are easier to consume within Power Apps. To avoid licensing costs you could just build a Power App that uses the Azure Cognitive Services connectors (still standard connectors) - you would not need a premium license or an AI Builder license. It will be more work and the Azure Cognitive Service connectors have not been updated for a long time and do not expose all the features, so you may hit some road blocks.