I was thinking there would be no manipulations in the top leagues before until recently that I saw that some players can intentionally play in a way to have at least one yellow card but which were later traced to betting fraud. But this is another one again.
Italian football is famous with manipulations and there are some big scandals in Italy from
Totonero 1980 to
Calciopoli 2006 and many smaller scandals. Italy can be a most famous nation with football scandals but I am not naive to think there is no similar scandals in other countries and leagues.
It can be individual player's illegal activities or at bigger scale like a club, some clubs cooperate with each other for their illegal activities in sports. At individual scale, it's hard to control what a player does.
Recently, we saw a case about an NBA player getting banned due to prop betting so this one is not that far off from becoming a reality. From how I see it, there's a decent probability for the case to be true once they get more evidence because if you were in the shoes of someone playing for a professional team, you'd always do what's best for the team and an unnecessary red card makes the situation questionable.
When they brought it to the light, I believe they already had already evidence, just want to find more by their announcement to expand their investigation further.
If they did not have any evidence, they will not announce it, knock the door of the club and player. When they do it, they actually knew many things and only want to make investigation expansion with more deeper proofs and connections with other players or clubs.