https://news.yahoo.com/news/kamala-harris-said-she-long-200919997.html

“I just think we have come to a point where we have to understand that we need to legalize it and stop criminalizing this behavior,” she said. “Actually, this is not a new position for me. I have felt for a long time we need to legalize it, so that’s where I am on that.”

As San Francisco district attorney from 2004 to 2011, Harris oversaw over 1,900 convictions for cannabis violations, the San Jose Mercury News reported in 2019. Still, only a small number of those people ended up in prison.

https://www.cbsnews.com/sanfrancisco/news/analysis-tulsi-gabbard-kamala-harris/

Harris “put over fifteen hundred people in jail for marijuana violations”

As attorney general, Kamala Harris would not have personally prosecuted drug cases. Local district attorneys would generally prosecute such cases so to say Harris “put … people in jail” as state attorney general is not accurate.