I contacted Brother Switzerland support today. I had to send them a picture of my toner. They confirmed my printer came with " toners permettant d'imprimer 2 600 pages en noir et blanc, 1 400 pages en couleur"...
So its not the TN248 available in shops or their XL versions.

They asked me to send photo of the toner where serial numbers are visible and where we dont see the reference like in other official shop original toners.

Its like special "startup toners" (to ers de demarrage) and they have a capacity between TN48 and TN48 XL versions.

I think both are wrong, I bought that from Digitec:
-Included toner for 260 pages: I dont think its true (too small)

-1000pages: it says "Fourni avec des toners permettant d'imprimer 2 600 pages en noir et blanc, 1 400 pages en couleur"
Source :
https://store.brother.ch/fr-ch...

I think its weird because its not corresponding to the standard TN248 toners which claims 1000 pages maximum...
I'd need to check the toners I got...