Way to expensive as a commercial stunt in my opinion.
The only explanations as an outsider that I can think about are:
- The game provider is going to take the loss for this
- their books are cooked so badly it's better to pay out rather than letting someone sniff in
If it's a marketing ploy, it's literally brilliant; if it's truly a mistake, they still honored the players' claims, regardless of the amount.
It could also be that they'll take it out on the programmers, but we can't know for sure.
There are various hypotheses, and we all know that many people write for clickbait.
Anyway, they also report 30 million here:
https://www.jamma.it/attualita/bug-sulla-slot-online-il-bookmaker-garantisce-pagamento-per-oltre-30-milioni-di-euro-di-vincite-339498