Why were there so few nasal vaccines for Fluenz Tetra children?

There may be many reasons for this, m.in. underestimation of the demand for the drug, introduction of free medicines for children, increased public awareness of the very idea of vaccination.

Here is a quote from the President of the West Pomeranian District Pharmacy Council in Szczecin:

"In fact, I can confirm that during the ongoing cold and flu season, the availability of intranasal influenza vaccine is severely limited. At this point, it is difficult to point to one main reason for this state of affairs, although of course the insufficient amount of vaccine that has reached the Polish market is one of them. For the time being, this is a fact. On the other hand, it should be noted that the number of vaccine doses that are delivered to pharmacies every year is a consequence of the course of previous flu seasons and the interest in a given vaccine, and this was not high in previous years compared to the intranasal vaccine."

Intramuscular vaccines are still available for sale:

https://www.gdziepolek.pl/produkty/95340/vaxigrip-tetra-przeciw-grypie-iniekcja/apteki