I have only been trading SPY and QQQ in an attempt to get/keep my small retail account "market neutral". To me, those ETF's have been functioning normally, of course with (sometimes record high) background volatility and volume. Putting that aside, notable to me is to see those ETF's "hard to borrow", although at (so-far) modest costs. Not surprising, given the understandable hedging demand.
I was working at a money manager during the Oct 19, 1987 crash. Although that was only one day, it was, IMO, functionally far worse than current markets. Then, S&P500 futures became grossly disconnected from the index, disseminated quotes were running 15 mins behind actual trade times, and Nasdaq market makers simply stopped answering the phone. (The NYSE at least was OPEN!)
While the last month has been a terrible melt-down, it seems to me that US equity markets (at least for the retail investor), have been providing a (more-or-less) properly functioning melt-down!
Can't speak to other assets, markets, etc.