Today I found these websites that are fully similar to the original ones and am curious to know is there any legal connection/interaction between Stack Exchange and these sites or those are some sort of phishing.
It is a (slow) proxy site; it accepts any domain name in front of
or links from your profile:
In other words, they are not specifically copying Stack Exchange sites.
Although it's only a proxy site, I would definitely not recommend using it, as there are possible vulnerabilities (feel free to edit or add to the list):
Cross Sub-domain Scripting - although sub-domains are considered different and will not pass the Same Origin Policy unless the
document.domainis tampered with, different browsers still behave differently
Cookies might be 'shared' - if explicitly named in the Set-Cookie header. Currently the login sessions are separate. i.e. logining in stackoverflow does not log you in stackoverflow.com.80bola.com
Cross Frame Scripting - Although unlikely, it is still possible for 80bola to use 2 frames to exploit a cross-frame-scripting bug to access private data on a third-party website
Man-in-the-middle - Depending on how the proxy is set up, there's a possiblility that traffic is visible to 80bola and of intercepting and manipulating the packets.
Adding a screenshot here for future reference in case the proxy is removed:
Lastly, I believe all the content and backlinks are giving them additional SEO juice to push them up the search ranking.