Not sure about market studies, but I don't think the data is going to be very encouraging for this case either. E.g. in early 2024 Amazon introduced ads in Prime Video, which people were already paying for. I couldn't find more recent data, but from this source at least it seems growth hasn't stalled much: https://www.businessofapps.com/data/amazon-prime-video-stati...

This is not a clear cut example because Prime comes with a lot of other benefits which is a confounding factor. Might be worth looking at cable TV subscription numbers after they introduced ads, but I couldn't find any data with a quick search.