No production for 3 months = no new cars and less used cars. Also, after the refresh was revealed, lots of people probably decided to go ahead and get used - either for cost, since the refresh is a big price increase, or things like yoke steering scared them off.
There aren't many used cars period.
Not as many new cars being produced as the market wants because of chip issues.
So many reasons for few used S's available - and none of those are a quarterly issue.