Yesterday I was presented with WeChat's Cookie policy for European users [1] for the first time, and they appear to have a European subsidiary, which could probably be fined. Of course they could just decide to fold that operation, especially considering (IANAL, but) the policy doesn't appear fully GDPR-compliant. I doubt that they are making significant profit in Europe anyway.

[1] http://www.wechat.com/mobile/htdocs/en/cookies_policy.html