Can you, or anybody else, explain that in plain English please?
I'll give it a go. (And you did ask - so you can only blame yourself!
).
Collateralised loans: As well as offering yield on deposits, Celsius clients can avail of collateralised loans. Someone may have a holding of Bitcoin or Ethereum (or other digital asset). They may not want to sell it but at the same time, they may want to borrow another asset - lets say a USD stablecoin - for a time, on the back of that collateral.
DeFi: When I have referred to DeFi in this thread, I'm referring to the emergence of a whole host of decentralized money markets and protocols that have developed largely around Ethereum rather than Bitcoin.
Staking: On certain blockchains, coins are 'staked' as part of the governance model and security model for the blockchain. Through staking, a holder of a cryptocurrency commits their tokens to support the network and confirm/validate transactions. The tokenomics of the cryptocurrency have been designed so that they get a yield or reward for doing so.
So I referred to Celsius investing in a staking protocol. On the Ethereum blockchain, the network is in transition as it goes about implementing major fundamental changes to the network. There are two networks running in effect. ETH is being 'staked' on the new network - and once staked, it cannot be accessed until this project is completed. So if you have staked Ethereum, then it's not a liquid asset right now. To offer a solution to this, a derivative product called staked eth ( stETH ) was created. In principal, 1x stETH = 1 x ETH. This is (supposedly) liquid and can be traded freely. Following the collapse of the UST stablecoin last month, many actors in the space reassessed what they were invested in - with renewed focus on the importance of trading digital assets that are liquid and can be bought and sold with ease. Consequently, liquidity in the pools or markets where stETH is traded dried up and stETH depegged from ETH. Celsius is a holder - on the basis that it collects or benefits from the yield that is currently offered on staked Ethereum. However, it now finds that its an outsized holder of this derivative in a market where liquidity has dried up.
There is a complex web of other markets and protocols but lets stop with the example above - as they don't get any easier to explain. Also, the example I've given is pertinent to the Celsius debacle as it's the company's stETH position that is central to its current difficulties (although it has others).
If there's anything that's not clear from the explanation above, let me know and I'll try and clarify it.
Celsius may have been insolvent for a while already or it may simply have boxed itself into illiquid positions with the result that it currently can't meet redemptions.