Users can't view anymore

Free users are very limited in what they can see. There is a list here of what free users can access Feature availability for users with Free licenses in the Power BI service - Power BI | Microsoft Learn bu basically to view reports they either need to be on a premium capacity or the on-prem report server or the user will need a pro license. 

So it sounds like your users must have been using a trial of the pro license. I think there are some circustances where the trial can be extended, but it sounds like this has now run out and your users will need to buy pro to view these reports (or you will need to put them on a premium capacity, but this is expensive unless you have hundreds of users)