All the contacts you've had at least one interaction with by email (from you to them) are imported from Gmail in folk.
These contacts are coming from Google contacts. folk will import contacts from these 2 sections:
"My contacts": people you have manually saved as contacts
"Other contacts": people you've interacted with in Gmail that are automatically saved by Google. You can start/stop automatically saving contacts at any time.
By default, Google is saving contacts you interact with by email on Google Contacts as "Other contacts". Here is an article to help you stop saving automatically contacts as "Other contacts" in Google or change your settings.
We import all the basic infos on your contacts:
We do not import labels from Google contacts for now.