Instagram log in error

Okay this is going to be a lot, but if anyone has any idea on how to help me, I’d really appreciate it. In 2018 I got an iPhone 8 Plus. I had a few Instagram accounts logged in. I hadn’t had the phone longer than 3 months and ran into a problem. All of my accounts got logged out and I was only able to log back into 1 through Facebook. That account is not my main account. Every time I tried to log into Instagram it would tell me there was an error. I could log in through my browser or any other persons app on their phone, just not my phones app. Eventually I gave up and now here I am 3 years later and got the iPhone 12 today. It is still giving me the same exact error. Someone said that when there was an Apple update in 2018, iPhone 8 Plus’s had a problem with Instagram accounts and never bothered to fix it. The only way people have got around it was making a new Apple ID. I’m only posting on this because I’ve tried reaching out to Instagram countless times. I think this is an Apple issue. How can I log into the Instagram app on my iPad with the same Apple ID, yet I can’t log into my brand new phone. I feel lost. I haven’t been able to see my friends posts my last 2 years of high school and then after that. I miss seeing what people are up to. I just don’t know what to do. It’s extremely irritating