I noticed some fake engagement

The quality of subscribers from a marketing perspective is simply low. They don't subscribe to make purchases but to watch content they like. This problem is not new, and one should think carefully before paying an influencer.

There's also a ton of bot traffic on general social media or just dead accounts. If you look at someone who's just become popular, their engagement can rival people with 10x the following. As followers are new and interested. Versus someone with a larger audience, who's been active longer, whose followers have gone through cycles of interest. But, there are just tons of people who pay for fake engagement/followers to inflate the look of their account. This sucks and can be done by advertising in other countries where clicks and engagement are considered cheaper so it inflates the performance of something but is real accounts, even though they may not be interested in the person themselves/what they're selling. Or simply paying for followers/likes/etc from websites selling fake bots etc. Both end up often with highly inflated followers and low to negligible engagement. I would focus on micro-influencers and building your own brand.

On Instagram, it is fairly easy to find out. A few agencies as well as influencers reached out to us to promote our product. They have got thousands and millions of followers base but the engagement was not even 0.001 %. So checking out the ratio between followers vs view count(usually not the first three pinned reels since their views are also paid) one can get an idea if they are genuine or not. The funny part they charge the standard rate of their fake-follower base.