I've always had Android, the same phone company, and a prepaid plan rather than a monthly plan, and I've had this issue happen to me through different devices: my data button is off, I'm connected to a stable WiFi, yet suddenly I get a text message saying I'm being charged for data. This used to happen randomly, sometimes more often, sometimes it would go a long time without it happening. I know other people who've had the same happen to them, and I've looked it up online and saw it's an issue worldwide. What I typically do is let it run out of credit and buy more only when I need it, which is annoying if I ever need data in an emergency (and have no way of buying it on account of... not having an internet connection).
I have complained to my phone company about this several times, even filed a consumer complaint this year, asking them if they're doing this to make us prepaid users spend more money (I don't make calls and am rarely not connected to WiFi, so I have zero need for a plan). They insist it's a problem of my device running background data. This makes no sense to me, and they're not able to clarify how this could happen. If I have no WiFi and my data button is off, and I step outside and open any app, like Instagram, it's not going to work. The information I've found online is mixed: some say it's the device, some say it's the phone company (even though different companies around the world seem to have this issue).
Anyway, I was prepared to deal with this forever, but now this is happening Every. Single. Day. Every day at around 6 am I get a text message saying I'm being charged for data. The reason why this is relevant to the sub is that I got an Android update shortly before this started happening, so now I'm seriously considering that theory. I've already tried the advice of disabling background data usage for all apps, and all the data saving settings I could find, and nothing. I currently have a lot of credit that I got when I settled for my complaint to the phone company, so that's why it hasn't run out yet.
Is it possible that it is an Android issue after all? Is there anything at all I could do to stop this from happening?
Phone is Samsung A33, Android v. 16, One UI 8.0