HMRC's recently issued DeFi guidance, which I have been assisting the Chartered Institute of Taxation (CIOT) with, is helpful at this time. 

In my opinion, both crypto and its uses commercially will grow significantly in the coming years, and so guidance, at least on some of the lending mechanisms is useful, not least to alert those individuals participating in DeFi lending, that there are various tax consequences. 

The UK taxation on debt can be complicated at the best of time, and that is only added to when you involve crypto.