Untangling the truth about Chinese debt and Sri Lanka means cutting through some misleading media narratives.
thediplomat.com
What you're stating is a myth.
It does not exist, full stop. You don't get to make things up, because it suits your narrative.
Gwadar port is already in the hands of the Chinese, in an own-operate-transfer deal. China will own and operate the port until 2049, and extract as much profit as it can, and transfer it back to Pakistan once the contract is up, regardless of if the Chinese managed to turn a profit or not.
No. SEZs are a bit different, as they're out side of Pakistan's tax code for a number of years, inexchange for a number of things such as infrastructure building, job creation, industrialization,...etc. Chinese companies are setting up industrial parks within Pakistan, outside of these SEZs. These WOULD be subject to Pakistani tax code, increasing Pakistan's over all government revenue.