Identifying users are who using Power BI Pro features

Hi all, I've been asked to find out which users in our company utilize Power BI Pro features. Currently everyone has an E5 license which includes Pro, but we're looking to downgrade the majority of our accounts to E3 which does not include Pro! I was wondering if anyone has methods to accomplish this? I thought of querying audit logs for specific Power BI activities, but I'm not sure exactly which activities I should be selecting.. If anyone has any experience with this I would appreciate any help, thank you!