Project longevity

For those that have been doing this for a while, is it considered normal to have a long list of projects for a few days, each with more than 70 tasks, then suddenly have less projects to choose from?

I'm not complaining at all or anything like that, just trying to better understand any reasons for this (i.e. do they not like my work 😅). Or does it simply mean that others chipped away at that task and now it's completed?