If you visit Google search from China, the SafeSearch option will on by default, and you can't turn it off (because it's already off in search settings). Login to Google will not solve this.
Visit Google's Non Country Redirection feature first will solve this problem. This userscript will automatically solve this issue for you. However, you need to wait when you perform a search request for the first time.
Tested in Violentmonkey.
Special thanks to @mengzonefire & the original author @opsomh.