We have experienced this and it is something to be aware of! We come across a creator that looks great, they have great video examples and we send them a brief to film content. When it comes to them returning content, we have high expectations then we realise they haven't filmed content themselves and that someone has filmed them in content, so the content they filmed isn't as high quality as the examples they sent in. This means we require revisions and it blows out timelines.
Instagram is one to be aware of, many photos and reels of creators looking amazing are often shot by photographers/videographers and have not been edited by the creator. TikTok is a platform where you can see what content they have filmed and edited themselves (but you can't message them if you both aren't following each other). So if you find someone you love on TikTok who is creating great content themselves - search for their TikTok handle on Instagram and reach out that way (they often have the same handle across socials or send them an email if they have their email listed!)
Always check creators are creating content themselves (and not having someone film and edit it with the creator featuring in it!)