I recently stumbled upon an advertisement for a free course from the University of Nicosia (UNIC), featuring an Introduction to Decentralized Finance. It's entirely free, no strings attached, and if I understood correctly, a verified certificate is also being distributed upon completion. The official starting date is tomorrow, 11th of October and is consisted of 6 weeks in total.
Course outline: (In weeks)
1. DeFi Fundamentals Professor George Giaglis
2. DeFi infrastructure: Ethereum and other L1 protocols
3. DeFi Applications I: Stablecoins, Lending and Borrowing
4. DeFi Applications II: Decentralised Exchanges, Synthetic Assets, Oracles, Insurance
5. Algorithmic Governane and DeFi Tokenomics
6. DeFi and Beyond
https://www.unic.ac.cy/blockchain/free-defi-mooc/Another free course about Digital currencies is also offered for free, you might want to check it out as well.
https://www.unic.ac.cy/blockchain/free-mooc/P.S I am in no way affiliated with the University of Nicosia.