Roaming data traffic with Data connection off

Hi!

I just changed my phone to an iPhone 14 Pro a few weeks ago.

Last week I've been in vacation, visiting 2 different countries outside European Union (me being a EU citizen with a subscription to Vodafone career).

When I got back home, I checked my extra cost with Vodafone and it seems that I've had some traffic on roaming, so I tried to investigate how this happened.

Whenever I travel outside of Europe, I am careful to uncheck "Data roaming" in settings, which I also did this time:

Of course, I did this before leaving the country. Also, I did not activate the Data connection in the foreign country for sure.

Even if I did this, it seems that I have some roaming traffic registered by both Vodafone and my iPhone:

How is this even possible? So with Roaming data Off and Data connection off, I've had some small traffic. According to Vodafone, the traffic was done at first heartbeat of the phone to the network (when I opened my phone in the foreign country, or countries, because it happened for both of the cuntries I visited). Strange thing is that when I came back to the first visited country, at the end of my vacation, it didn't happened again.

It's the first time this phone gets out of the country so it's out of the question that the data is older. For sure the roaming traffic is from the previous 2 weeks (since I changed it) and this is the only time that I was our of the country. So for sure, with Data off and roaming data off, my iphone had managed somehow to activate the data plan and transfer those few KB (when I started the phone). Also, for sure I did not, by mistake, activated the data connection (and even if I did, having the roaming data deactivated, should prevent traffic - but for sure I didn't activated the data).

If it's important, I am using an eSIM, not a physical SIM card.

Any opinion on this problem? Should I get my phone checked? The thing is that I don't want this to happen again in the future, so I am trying to undestand if I have to send my phone in service for a check (although I don't know how they will be able to check this).

Thank you!