Installing PNPM Package Manager on Debian/Ubuntu?

I do not believe -fsSL is a valid option.
Maybe you mean to use one of the following options.
LINK to curl options

 --ssl           Try SSL/TLS
 --ssl-allow-beast Allow security flaw to improve interop
 --ssl-no-revoke Disable cert revocation checks (Schannel)
 --ssl-reqd      Require SSL/TLS

 -f, --fail          Fail silently (no output at all) on HTTP errors
     --fail-early    Fail on first transfer error, do not continue
     --false-start   Enable TLS False Start
 -F, --form <name=content> Specify multipart MIME data
     --form-string <name=string> Specify multipart MIME data
     --ftp-account <data> Account data string
     --ftp-alternative-to-user <command> String to replace USER [name]
     --ftp-create-dirs Create the remote dirs if not present
     --ftp-method <method> Control CWD usage
     --ftp-pasv      Use PASV/EPSV instead of PORT
 -P, --ftp-port <address> Use PORT instead of PASV
     --ftp-pret      Send PRET before PASV
     --ftp-skip-pasv-ip Skip the IP address for PASV
     --ftp-ssl-ccc   Send CCC after authenticating
     --ftp-ssl-ccc-mode <active/passive> Set CCC mode
     --ftp-ssl-control Require SSL/TLS for FTP login, clear for transfer

I have no idea about the | sh
What I would suggest is you go to https://curlconverter.com
Paste your curl command into the "curl command" textarea and if there is an error they will point it out for you.