When attempting to migrate a Managed Metadata to an Office 365 public site, the following message appear:
Sharegate is unable to copy term group properties due to Office 365 public site limitations.
This error happens because Office 365 public sites do not support certain function in the term store. Sharegate cannot copy the term group properties because Office 365 public sites do not allow this operation.
Sharegate is able to copy the term group but without its properties.
You can manually configure the term group properties in the Office 365 global administration.