Is my cell phone operator allowed to limit my EU data roaming?

My Norwegian cellular provider has given me a two month deal where I can use 50 GB of cellular data per month. After this 50 GB limit, I have unlimited data, but at very low speeds.

I traveled to Sweden with this plan, and received the following term in an SMS:

I EU/EØS bruker du av min/SMS/MMS som er inkludert i abonnementet ditt, samt inntil 10GB av datamengden.

My translation:

Within the EU/EEC you use the SMS/MMS that is included in your subscription as well as 10 GB of the data.

Customer care have informed me that for EU roaming data usage, the speed will be limited after 10 GB, as opposed to 50 GB for usage in Norway.

The official EU website says:

You pay exactly the same price for using these services when travelling in the EU as you would if you were at home. In practice, your operator simply charges or takes your roaming consumption from the volumes in your domestic mobile tariff plan / bundle.

Is my carrier allowed to give me a separate bundle for EU usage? The EU quote makes it appear that the same bundle should apply to both.

My carrier's customer care department argues that this two month period is a "test period" and that during this "test period" they're allowed to discriminate between domestic usage and EU usage.

Are they correct? Is this allowed?

Edit: It might not matter to the answer, but it turns out that the customer care misinformed me, and that they actually do not limit the speed in the EU, instead they charge (80 NOK per GB) for EU use after the cap.