I can't login Instagram app but I can on web

So when I try logging in the Instagram app, it says "Incorrect password," and when I forcefully login using the "Forgot Password" button and having it send a code to my email, either by manually typing in the code or clicking the "Log in without changing password" button link in the email, they both say the same thing: "Oops, something went wrong. Please try again."

I have no problem logging into the web version. It's only the app that has this problem; and I can log in to multiple accounts on the web version, but no accounts on the app version. I have deleted the app and redownloaded it several times. I've even left it off my phone for several weeks at a time then tried again with the same issue. I don't use Facebook or any other Meta apps nor have them installed on my phone; only Instagram. I have restarted my phone several times, reset modem/router, everything. This problem has persisted for several months now. My iOS is up to date.

What I think I need is the ability to delete temporary files/cache on my phone that's not just Safari. Any ideas?