Says the Wall Street Journal:

Even for veteran pros in a seen-it-all trade like oddsmaking, the spring sports shutdown was uncharted territory. Expertise was hard to come by. A lot of action wasn’t on television. Nobody had a clue when sports as we knew it were going to come back.

The rest of sports, of course, came back—in a huge way, and almost all at once.

By September, there were days in which it was possible to place a bet on basketball, hockey, baseball, football, soccer, and more. The Kentucky Derby was run. The U.S. Open happened in both golf and tennis. Crucial, stabilizing mother ships like NFL and college football returned.

Betting surged, especially online in states with legalized sports betting.

https://www.wsj.com/articles/what-does-home-field-advantage-mean-in-a-stadium-without-fans-11605799111