Agree with FStrat and Marlowe. What really matters is the quality of pre-health advising and placement rates. Both are supposed to be quite good-to-excellent and improving. A smaller number of applicants can actually be a good thing as it suggests less of a queue for advising, more personalized attention, etc.
Another thing to remember is that UChicago’s enrollment in the Fall of 2015 (around the time that some in that 2018-19 cohort was just entering college) was under 6,000. The entering class this fall will be joining a college community of about 7,000 total which is where the College is expected to hold steady for awhile. The Classes of '21 - '23 had an average of about 225-250 MORE enrollees than did the Class of '19. So the number of med school applications is very likely to increase. We won’t fully see that impact until at minimum the 2023 cycle (which will include some from Class of '23 and others from earlier larger classes who gapped a year or two). It might even take longer. And in the meantime, peers could be upping their numbers as well. It’s all good, as long as the support and the placement is where it’s supposed to be for any of these excellent schools.
BTW, happened to be on the Columbia website today and noticed that their average “successful” GPA/sGPA for admission to allopathic med school is 3.59 and 3.55, respectively. That’s lower than UChicago! (3.66/3.58s in 2019).