Valve deployed a massive banwave against cheaters the day after ending the Steam Summer Sale. Over 40,000 players lost access to Steam servers thanks to the VAC ban, while 5,000 individuals received complete game bans.
This is an unprecedented number, considering that VAC normally hands out between 3,000 and 5,000 bans per day. On 6 July 2017, Valve opened the floodgates and clamped down on 40,445 cheaters. Presumably to prevent people who had already been banned from taking advantage of low game prices and playing again.
VAC bans don’t actually prevent players from playing their games. Rather, they are prevented from connecting to Steam servers; blocking them from using their skins and cosmetics. It also prevents them from selling the skins and cashing out after the ban has been handed down.
Forty thousand bans doesn’t actually sound as high as we would have expected from Steam; considering the number of players on Dota 2 and Counter Strike: Global Offensive. Valve is likely to be erring on the side of caution in this event, since it’s already dealing with such a large number of players.