[BUG] Installing latest npm downgraded me from 7 to 6 and now I can't install anything

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I tried to publish a package and got:

npm ERR! 426 Upgrade Required - PUT http://registry.npmjs.org/@shaderfrog%2fglsl-parser

Ok I guess it's time. According to: https://github.blog/2021-02-02-npm-7-is-now-generally-available/

Please note, npm 7 is now published as latest to the npm registry and will be the default version installed when you run npm install --global npm

Cool. So I tried:

$ npm --version
7.21.1

$ nvm ls
->      v16.2.0
         system
default -> 16 (-> v16.2.0)
node -> stable (-> v16.2.0) (default)
iojs -> iojs- (-> N/A) (default)

$ npm install --global npm
npm notice Beginning October 4, 2021, all connections to the npm registry - including for package installation - must use TLS 1.2 or higher. You are currently using plaintext http to connect. Please visit the GitHub blog for more information: https://github.blog/2021-08-23-npm-registry-deprecating-tls-1-0-tls-1-1/
npm notice Beginning October 4, 2021, all connections to the npm registry - including for package installation - must use TLS 1.2 or higher. You are currently using plaintext http to connect. Please visit the GitHub blog for more information: https://github.blog/2021-08-23-npm-registry-deprecating-tls-1-0-tls-1-1/

removed 69 packages, and changed 103 packages in 1m

$ npm --version
6.13.0

You can see it downgraded my npm from 7 to 6, and now I can't do anything due to npm ERR! code UNABLE_TO_GET_ISSUER_CERT_LOCALLY errors on any npm networking commands.

Expected Behavior

Installing npm to install npm 7 and remove the TLS errors.

Steps To Reproduce

1. On any environment afaik
2. Node 16 installed by nvm
3. Run npm install --global npm from the official instructions

Then your npm is downgraded to 6.

Environment

• OS: MacOS
• Node: Node 16 via nvm
• npm: Broken

Start by reproducing the reported commands with Node 16 installed through nvm, checking the npm version before and after npm install --global npm. Investigate why the global install selects npm 6 and produces certificate errors; done means the official install path keeps npm 7 and npm networking commands work without the reported errors.