Where is this $20B number coming from? It doesn't appear to reflect reality.

https://www.axios.com/riots-cost-property-damage-276c9bcc-a4...

I stand corrected and edited. Its still a non trivial amount and apparently "most expensive riot in history" according to your source.

There's some apples to oranges going on there.

You'll see in the top ten list several listings in April 1968, when Martin Luther King was assassinated. Counting these (and the many, many other cities they took place in in 1968) separately, while lumping together "protests that took place in 140 U.S. cities this spring", is fairly hard to justify.

You should also consider what else your preferred news sources may have blown out by a similarly inaccurate 10-20x amount about the BLM protests.