> This study seems unconvincing. We see that black drivers are pulled over more during the day - why does that necessarily mean that it’s due to their race?

Because on the day time shifted an hour artificially due to daylight savings, the racial discrepancy moved by an hour, even though the sun physically didn't.

(The alternative explanation is that black people all decide collectively to drive worse/better when daylight savings changes twice a year. Which seems... unlikely.)

It's an extremely clever approach. I'd encourage you to at least skim the article rather than asking questions it readily answers.