There was a well-known case of an elderly non-Jewish woman who, on her deathbed, began quoting whole sections of the Zohar in its original language (she knew neither Aramaic nor Hebrew).
In that case they actually did the work and traced her life story, and it turned out that in her youth she had worked for a certain period as a maid in a Jewish home, where the master of the house would sit at the table and study the Zohar aloud, and apparently somehow her brain absorbed the material, and during illness, in a twilight state and amid hallucinations, it surfaced.
I would bet that in the present case too, a good investigation would find the source.

There is a big difference between an old woman and a two-year-old child who sometimes is not even fluent in his own mother tongue.

There is a difference, and still, a good investigation presumably would have found the source.

Fine, people here may not be up to date, but the Rabbi too? They already found the explanation for it:
https://www.mako.co.il/tvbee-articles/Article-173dbb809b6a361006.htm

First of all, I’m not sure they found the explanation. The explanation too needs checking. But what is so surprising about me not being up to date? I heard and responded to the facts as I heard them. If there is an explanation — excellent.

My filter blocks me from that link. Could the scientific updater kindly copy here what is written there for me?
Thanks!

“But one particular hypothesis caught our eye more than the others. One of the comments said that the child ‘watched too much Peppa Pig; if they put on Yuval Hamevulbal for him he’ll start speaking Hebrew.’ A conspiracy theory involving children’s TV shows? Just say ‘a case that belongs on tvbee’ and be done with it. And indeed, careful listening to George from the original British version of ‘Peppa Pig’ revealed what can only be called a chilling resemblance to the accent of the child in question, and also to his vocabulary.
Did you notice the similarity in the pronunciation of the word ‘Dinosaur’? Because we did, and we haven’t been calm since.”

Very interesting! It really does sound like the same accent.
Does this really solve all the issues too, including the scales and the key and things like that?

Moshe, there are children’s Peppa Pig videos that deal with using scales, and keys. Whether that answers it or not — you decide.
It reminded me that a few years ago I heard about a friend of a friend, here in Israel, whose child had a speech delay and then suddenly started speaking Spanish even though at home they spoke only Hebrew, and the number of Spanish words they themselves knew could be counted on one’s fingers.
But since his parents were rational Jews, for whom the theory of reincarnation was not the first thing that came to mind, they investigated and discovered that the caregivers at the child’s daycare spoke Spanish.
If he had been born in Majdal Shams, presumably they would have made a television program about him.