The mobile hotspot is not working on my 12 pro max

Ever since I got my iPhone 12 pro max, the mobile hotspot functionality has been a hot mess. I'm using the hotspot to tether my internet connection from my iPhone to my 2018 iPad Pro. It was all working great on my old iPhone X, 2 buttons pushed and I was on. However, this basic functionality does not work at all on my iPhone 12 pro max, using the exact same SIM card as I used in the iPhone X.

I can create the hotspot no problem, but every time I try to connect to it, be it through wi-fi or bluetooth, the internet connection is not working, it is just displaying a "No internet connection" text under the connection, and a spinner keeps going on forever.

I have contacted Apple Support about this issue, and through some miracle and multiple restarts, I was able to connect (even though I've done all the steps myself before my call with Apple after countless hours of searching online). However, the happiness was short lived, because since my call with Apple Support, I haven't been able to connect at all again. Every single time I try to do it, the "No internet connection" text appears, and I can't use the internet.

This is just ridiculous, a 1300 EUR device that can't use a functionality as basic as mobile hotspot. I'm seriously considering returning the device and going with a different phone, this has been so frustrating.

What I've done so far (countless of times):

• Restart the iPhone
• Restart the iPad
• Reset network settings on iPhone
• Reset network settings on iPad
• Try to connect with Wi-Fi turned off and bluetooth on
• Try to connect with Wi-Fi turned on and bluetooth off
• Sign out and back into iCloud
• Turn mobile data off and back on
• Turn wi-fi off and back on
• Turn bluetooth off and back on
• Another tens of combinations of the above steps.

Both devices are running the latest version of iOs and iPadOs respectively.

Hopefully someone can shed some light on this issue, it would be a shame to return a device I really enjoy using because a basic functionality is not working.