Programmatically disable blocking of private network requests in chrome sandbox

Question

I'm using chrome-devel-sandbox bundled with puppeteer, and I need to disable blocking of private network requests. I am seeing this error:

Access to XMLHttpRequest at 'http://127.0.0.1' from origin 'https://example.com' has been blocked by CORS policy: Request had no target IP address space, yet the resource is in address space `local`

I tried the solutions in this answer, but these preference files seem to have no effect, and upon launching puppeteer the "Block Insecure Private Network Requests" flag in chrome://flags is reset to the defult value.

1. Shouldn't the --disable-web-security flag take care of this already?
2. Is there a way to set this preference via a flag?
3. Is there a preferences file that the sandboxed chrome will honor?

Looking at strace logs, it does appear that the sandboxed chromium process opens the file:

[pid 1177626] stat("/etc/chromium/policies/managed/dev_policy.json", {st_mode=S_IFREG|0644, st_size=236,

I even tried --no-sandbox without success.

I'm using Chrome 99 on debian.