For clarity 3,900 tons over four raids and 1,500 planes.
I’m not sure how to translate that into modern munitions but I’m also uncertain why a strategic bombing death toll should tell us anything about Iranian protester deaths. Iran isn’t doing strategic bombing of their citizens, they’re using small arms across hundreds of locations.
The linked article cites a source [1] with detailed methodology for their actual claim of 7,000 deaths and mentions that other unmentioned sources claim it could go as high as 30,000. I don’t see any claim of that being in a single day.
Given the timeframe and widespread nature of these protests it doesn’t seem implausible.
[1]: https://www.en-hrana.org/the-crimson-winter-a-50-day-record-...