Weird Instagram comments

I just posted a few pictures I took this week and as soon as I posted the first one I started to get "Send me this post" comments. Now I've finished posting and I got comments like this under almost every post from three different accounts.

The accounts are global.photographying (277 posts and 76k followers), thewildlife_diary (368 posts, 90k followers) and Nat Geo.diary (1400 posts, 2k followers). Global photographying and thewildlife_diary claim to be a promotion hub in the description and all of them make post crediting the accounts they got the photos from. They're also liking my posts.

I've never seen this and it feels kinda shady so I just wanted to know is somebody knows what this is and if it's actually some sort of shady thing?