The distribution of IP addresses depends to a large extent on 4G provider. Some of them reuse IPs and you can get the same IP after you change network mode 4G > 3G > 4G.
The same applies to IP addresses allocation space.
You can request IP change as often as you want. Resetting network mode takes 5-10 seconds.
There is not rate limiting. From time to time reconnection fails but it has nothing to do with rate limiting. Sticky IP is an issue for some 4G providers but, again, it has nothing to do with rate limiting
Keep in mind that this behavior will be a significant outlier in ISP analytics - they will notice you eventually, just like they’ll notice 10 seemingly synchronized Huawei modems connecting to (and disconnecting from) the same base station.
That’s all to say - be careful using this for any nefarious activity. It’s not inconspicuous.
In Australia it's not possible [1] to get SIM cards without identification. So getting on the radar of the security folks at your telco could easily end with you never being able to use that telco again.
