Hi there.
On how many ig accs can i insert a .com url in bio. Before it gets flagged/or the acct banned.
I’m not going to spam it. I wanna now for sure if i can use a .com url on 3 accs.
Thank you.
Edit 1: the redirect will be to the same server ip for now
I wouldn’t use it on more than 1 account. Still, it highly depends on the content that’s on that website.
The main issue you have here is footprints. 
Right off the bat good on you 
for acknowledging the IP issue on top of the .com domain itself. Not trying to be jerk-ish or anything it’s just that most people don’t follow the footprint trail
further along down the path than what is obvious to them at the start of the journey.
So let’s unpack the question you have as it’s a popular and common one here. Just follow along the one strand (what IG could possibly see and collect data on for a URL in a BIO) of the IG web.
As we think from the IG algo perspective (my opinion only):
They will check your bio for any flags, filter trips based upon your word choices and other metrics gathered based upon further ‘up the line’ of data collection with the account. So lets assume that by the time they hit the content of the bio they already have made quite a few determinations about your account based upon creation, ip, etc…
They’ll crawl your link and see where it re-directs and ends up. They’ll compare that to the data they have on on that target domain, IP, what other accounts are in the database with that target IP, .com what determination they’ve made about those related accounts, and take that (and I’m sure other unknown to us peons things) into consideration.
RELATED NOTE: To expand a bit on one of these points there is something known in Google parlance as a bad neighborhood when it comes to IPs.
EXAMPLE: Think of it as when you were growing up and your Mom would know who the “bad kids” 
were that you were not allowed to hang out with because she knew what the deal was with them and you didn’t because you were a kid.
I mean they were cool and all and you wanted to hang out. But Mom knew better 
on what kids were gonna end up in jail and there was no way her kid was gonna mess around with those kids. Oh dear god I think I just had a therapy moment…sorry
For a little more reading on bad neighborhoods (although more related to PBN’s and such) check out this:
What is a bad neighborhood
Bad Neighborhood checker for fun and stalking
Wow this is getting a little long…
Back to the subject of IG .com and URL. 
The reason I’m harping on this is that although G and IG are two totally different animals it is reasonable to assume that the principals are the same. The execution is just different due to the differences in each channels purpose.
In my opinion -> multiple URL’s going to the same .com especially through redirects (don’t think they don’t know what you’re doing and doing redirects kinda tells them you know what you’re doing isn’t kosher 
) with any type of asset that you want to keep is a risky position to take.
This is just based upon the wealth of data already gathered on the account prior to following any link put in the bio that help make a determination (thanks Mom!).
OPTIONS
There are quite a few smarty-pants 
people on here with some very very good methods and options to consider with your linking.
Here are two of my faves:
Salamouna’s sneaky deaky Google Docs method
Adnans “Hey everybody I found a use for Google+!” method
Final Chapter of “War and Peace”
What do I think is the best course of action (and what do I do not saying it’s right or I know it all)?
Why risk it if you don’t have to? Get a few of those .88 domains get some cheap hosting. Here is an example of $1.99 for a year hosting and I think they have different locales and “bam” you’re already ahead of the game.
I’m of the mindset that if you’re going to do all the work, all the investment of time,energy, and money, to get to the point to have a viable account to work to monetize…why screw it up and risk it over something like that?
Again this is all my .02$ your results may vary. But it works for me 
nice. thanks you very much.
edit1: trying to find some cheap deals for " hosting + domains " and i will see what i can do
hahaha, sure sounds like me there 