Whats a good PLG company of the recent years that use Customer Referral as a strong growth channel? (ex: in the past, Dropbox “get 1GB, give 1GB”)

Canva and Airtable I would say have great Referral programs. For Canva: Refer a friend to Canva and receive a credit to exchange for a Premium Canva element like stock photo, icon, or illustration. For Airtable: Refer a friend to Airtable and receive a $10 credit towards any paid Airtable plan.

Very interesting referral strategies have Tinkoff bank from Russia. Refer a friend and get 5000 roubles for your friend with a special condition; most of them finished successfully. Success rate was about 70%