Lte+Proxy reels won't upload

I want to know if you also have this problem, on Facebook the videos upload normally to me and on Instagram they do not And since it is the same company it should work here and here. For the time being I don't have access to a computer and fiber optic cable so I am using on my phone on instagrams without Proxy but I would already prefer to separate accounts with a separate ip

Yeah, you'd think since Meta owns both they'd run on the same principle for both platforms. However, it'd seem IG might have stricter backend filters, particularly with mobile uploads or when on the same IP across multiple accounts (on it's own not an issue, I have several private accounts on my home IP and they work just fine, but yeah: private accounts).
Separating IPs, using mobile proxies (whichever works best for you) could help reduce some issues. Ideally you have an extra device too.

You can still use your accounts on different Ip's. That is fine

I use ISP proxy, I will try to buy a mobile proxy and see if using it I can upload reels. Want to manage max 3/4 accounts on phone. Soon I will have access to a laptop so managing separate profiles will be easier. Can I use vpn+proxy on my phone for Instagram accounts or is it not possible?

After using a computer, you’ll notice uploads from a phone get more views than computer.

I was looking at mobile proxy prices, for one Instagram account I would spend a mininum of $300 with a consumption of 1gb per day, the cheapest offer on the month I found for $50 for 1 IP address.
I pay a few dollars a month for ISP proxy and never got banned because of it, is there any confirmation that mobile proxy improves the reach and performance of the account? I only want to ultimately support a few Instagram accounts, so I think I could stay with just a SIM card and a new phone, to be honest.
I'd like to use vpn on this phone along with the proxy, but I don't know if that's possible and if vpn won't replace the ip address for Instagram.