Normally I'm pretty sceptical towards these bonus bets, but here it got you an extra 3000 NOK win, as the max win on a 2.50 bet would be 12500. Seems it calculates the 5000x cap from total bet (3.50), which is actually pretty fair.
Some would claim this is a 6142x win, since 2.50 is the base bet, at least I've seen some full screens of top symbol on Book of Shadows announced as 10000x wins.