Why does an app I got say “get” all the sudden

I got Snapchat in the App Store somewhere in 2020 I think and recently (a few months ago) I uninstalled it because I didn’t have much use for it. But today I saw in the App Store Snapchat being promoted and it said “get” next to it. I thought it was a different Snapchat but when I went back to check my apps I owned, Snapchat was gone. I, without a doubt, swear I got this app before which is why I’m confused how this happened. I know I can just get it again and reinstall it but I want to know how this happened and if I can replicated with other apps if possible. But I mainly want to know how this even happened!?