After rebuilding from 2.9.0beta5 to 2.9.0beta7 I noticed that some variables were reset: topic views heat low, topic views heat medium, and topic views heat high.
I can find no record on my forum of these having been changed.
How odd. I’d recently set them quite low (in the hundreds) but today they were something like 1000, 2000 and 3500. Maybe I should rebuild Discourse and see what happens.
Do you happen to have the automatic topic heat values setting enabled, which is the default? If so as the description says it will adjust them based on site activity.
Same on one of my forums. It’s a login required forum with around 30 users and it chose settings not too far off from the ones you reported so I ended up turning it off.
On a really large forum I’m a staff member on the automatic adjustment does a lot better at setting reasonable values.