As football is one of the most popular games in sports gambling and its updates are very important for gambling. Many times the result of the match changes on the basis of yellow and red cards, so in football cards showing is important and also for gambling. The main purpose of opening this topic is to get familiar with white cards.
The interesting thing is that this card only exists in Portugal, it was created in 2018, so it's not exactly "new". This card does not exist in any other football rules and is not even endorsed by FIFA or Ifab.
I think it could actually be Green, which would be the "opposite" of red, since its intention is to signal an attitude exactly contrary to the fact that generates an expulsion.
The curious fact is that only five years after the introduction of this card in Portugal, it was "presented". Was there nothing in that period that deserved a white card? Or did most referees consider him unimportant and didn't even want to take him to the football field?