2020 and 2018 "flash crashes" did not exhibit prolonged volatility runups. They were volatility spikes. All major volatility spikes on VIX are followed by a downtrend with intermittent volatility spikes. This holds true the time period of listing.
Going back to '91, there are 3 instances of VIX in a prolonged uptrend. These are 1996-1999, 2007-2008, and now in 2022.
When the 19.34 resistance on VIX becomes support, it is typically followed by a long period of volatility and a bear market. 19.34 on VIX is clearly a critical resistance/support mark for major market events.