I've been testing stuff for the past few hours regarding this.
It would seem that Jagex has beefed up their detection on tutorial island by a lot, far too much actually as I am able to get accounts both locked and not locked depending on what I do. As far as I'm concerned, the IP you play on and the IP the account was created on does NOT matter at all. This is solely behavior based. So if your accounts are getting locked, you'll need to change up the way your script works. If you're using a public tutorial island script and this is happening to you, you're probably best off finding someone to make you a private one.
For anyone wondering, the last two accounts I made before typing this were: hand made, played on the same IP and through the osbot client. I ran them through tutorial island 1 at a time, with about a 2 minute time difference from logging into the 2nd one after logging off the first. The first account was NOT locked but the second account was locked and there's a reason for this because I had done something different on the first account. This of course was just one sample but there were two other accounts that I was able to not get locked a few hours prior which I had done similar things to. I will test a few more accounts later and come back and edit this to confirm with more certainty as I don't feel like doing more tut accounts right now.
Again, for the paranoid people who think their IP's are flagged, its not the reason.
EDIT: I have done some more testing along with the help of @Chris and my cousin. I'm pretty sure what Jagex is doing is locking any accounts that are put through tutorial island via a proxy or VPS. I had my cousin run two accounts by hand on his laptop, one through osbuddy and one through firefox. He dorms at college so it was through his colleges wifi. Both of the accounts were created successfully. @Chris did the same thing. He ran one account by hand on his home PC through his home IP on the osbot client. The account was NOT locked. He then did the same thing except this time ran osbot through one of his proxies and the account was locked after completing tutorial island. I also did the same thing, ran an account through by hand on osbot via a proxy and the account was locked.
This would explain why we're not seeing a bunch of posts on reddit about people saying they made a new account and it getting locked. Your average rule abiding runescape player isn't creating their new PK account on a VPS or through a proxy.
For those wondering, you CAN bypass this. I can run an account by hand through a proxy or on a VPS and still not get locked. The detection they're using is behavioral so like I said above, you're going to have to change up the way your script works. I'm not going to tell anyone exactly what to do but just know it is obviously possible. I will edit this again when I have successfully implemented what I'm doing by hand into a script and will let yall know when I can successfully run bots through tut. If anyone has any useful info to add on or to disprove what I'm saying, feel free to say it.