New PnPTerm Specified argument was out of the range of valid values - pnp/PnP-PowerShell GitHub Wiki

The New-PnPTerm example states that the LCID is not required.

New-PnPTerm -TermSet "Departments" -TermGroup "Corporate" -Name "Finance"`

Without adding the LCID, however, I would get the following error:

New-PnPTerm : Specified argument was out of the range of valid values.
Parameter name: lcid

By adding a LCID of 1033 the term is successfully added to the term store.

New-PnPTerm -TermSet "Departments" -TermGroup "Corporate" -Name "Finance" -LCID "1033"`

New-PnPTerm -TermSet "Corporate" -TermGroup "Departments" -Name "Finance" -LCID "1033"`

Additionally when you incorrectly place the TermGroup in the TermSet field you get the following error message

New-PnPTerm : Specified argument was out of the range of valid values.
Parameter name: index`

If you see this message check that you have your TermSet and TermGroups in the correct fields.