The initial drop in player numbers due to bans was quickly followed by a sharp increase, reaching nearly 150,000 active players (almost 142,000 at the time of writing) compared to the previous 90,000. This indicates that many players returned to the game once the bot problem was resolved.
Fan pressure on Valve demanding a solution to the issue clearly bore fruit. Campaigns like #FixTF2 forced the company to act, which yielded positive results. Valve resolutely refused to reconsider ban decisions, as evident from support messages stating that the bans are permanent.
Team Fortress 2 is currently undergoing a revival, and the number of active players has increased significantly.
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Image source: SteamDB
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Cover author: Valve. Cover source: IGN