Non-approved VPNs used to circumvent the great wall are absolutely illegal, though largely tolerated (and observed), but the authorities can and have used them as an excuse to bring people in.
Source: have actual been to China and played the whole “which VPN will work on which network” game many times.
VPNs are not illegal in China. And one can use it to circumvent any restrictions.
Non-approved VPNs used to circumvent the great wall are absolutely illegal, though largely tolerated (and observed), but the authorities can and have used them as an excuse to bring people in.
Source: have actual been to China and played the whole “which VPN will work on which network” game many times.
I assume all vpn services accessible from china are run by government and they monitor the traffic