It's serious, That is how IG works sometimes. We have had our new accounts getting blocked or banned sometimes for no reason, the accounts which we create for our mother child service or anything in general. Though the golden rule for any account to keep it going in the start is :
1.After creating an account, go very slow with whatever you do. Let it be posting, or any activity in general.
2.No links in bio atleast for a month until the account is created.
3.If you follow or dm users, start very slow and below the normal limits IG gives you.
4.Add a physical sim card number, email with a good email provider like gmail,gsuite or even outlook. Avoid russian, spammy or temp email providers at all costs.
5.Add 2fa or connect your facebook accounts, it's a +1 to tell IG that this account is genuine and not spammy.
6.If possible run ads for a few $, Every company gives priority and trust to those accounts who pay them.