Yes, UCD seems to be stingy about posting the Common Data Set.
I couldn’t find anything for 2021-2022, but here is a link to the CDS for 2020-2021: https://aggiedata.ucdavis.edu/sites/g/files/dgvnsk1841/files/media/documents/CDS_2020-2021_Davis.pdf
CDS 2020-2021
Number of qualified applicants offered a place on waiting list: 13,092
Number accepting a place on the waiting list: 4,960
Number of wait-listed students admitted: 3,919
Also, here is a link to a post from last year with UCD historical waitlist data going back as far as 2012: UC Davis Waitlist 2025 - #32 by 20172021