This problem is not coming from your Joomla and WordPress sites that because your email is shared somewhere on your website or it is listed in their spam tool. To solve this, you can setup an email blacklist in your hosting for qq.com.
I have ever faced same problem and solved it by doing that. I hope it helps!
USe captcha in forms ..thats the best way to protect your forms. Also display the email addresses as an image but not as direct mail to text. if someone is intentionally spamming you..its hard...but try some good spam filtering service.
Captcha is just the one aspect of the whole problem. Sometimes spammers are alive people trying to reach the goal of dumping the web space around them. I'm familiar enough with the Instagram problem, but I have the clue - https://spamguardapp.com/ app. Maybe someone has used it already?