That information is out of date and was revised in mid-August 2020. The precise specfics were not given; however, inspection revealed that:
For TL3, I think the number of topics read over 100 days in 300. The number of post read over 100 days most likely dropped to 3,000 (but definitely not more than 3,500). the likes given are also on a 100 day rolling average.
https://us.forums.blizzard.com/en/d3/g/trust_level_3?order=added_at