Trading in bitcoin based on obligatory precaution is haram, as per Ayt Sistani, however, we can refer to Syed Hakeem on this matter as per my knowledge

In cryptocurrency, DEFI (Decentralized finance) coins are a relatively new phenomenon which are used to provide a platform to users where all financial activities are conducted in a decentralized way i.e. no involvement of bank or lawyers. The technology used is based on smart contracts where all the formalities and agreements are coded in the blockchain between a borrower and lender so in case of default or non-payment by a borrower, the lender is given the right to property (or any other asset) of the borrower. In the normal world, banks decide who to lend the money to but in decentralized finance, any borrower can borrow from any lender they wish. Of course, there could be involvement of interest between the borrower and lender

In such a scenario, can we invest in DEFI coins?

As it it involves interest based lending (Riba), it is not permissible to invest in.