I have some waitlist data posted in the Waitlist discussion here: http://talk.qa.collegeconfidential.com/t/ucsd-class-of-2025-waitlist-discussion
The # of waitlisted applicants has increased over the last few years and the # admitted varies from year to year. Last year, the UC’s admitted many students from the waitlist probably due to student’s taking Covid Gap years. No way to know how many are waitlisted this year but check out the #'s for 2019. No data for last year or 2018 on the common dataset.