A state-of-the-art new Queens library that took $41 million to...

Hedge fund Darsana Capital Partners has cut the value of its investment in Juul Labs by more than a third, a report Friday said.

The write-down values the San Francisco-based company at $24 billion, the Wall Street Journal reported.

The move comes amid a proposed federal block on flavored pods and investigations into an outbreak of vaping-related illness, developments which have dimmed the e-cigarette maker’s prospects.

Darsana and other hedge funds had seen big gains in their Juul investments last year following the e-cigarette maker’s deal with tobacco group Altria.

Sources told the Journal that Altria’s investment in Juul is now valued at $225-$230 a share, down from a high of $300 this summer.

Sales growth has slowed significantly this fall. For the four weeks ended Sept. 21, sales for Juul products rose 31%, versus 56% growth for the 12-week period ended the same date.