if you had a capital loss of $21395 in 2020 $300o of tat was used in each year 2020,2021,2022 so 12395 c/f would be right for 2023.
the exception would be if with that loss you had negative AGI for one or more of those years, then depending on how negative some or all of the loss wouldn't be used.
included is the worksheet to figure the CLCO from 2020 to 2021 on page D-11
https://www.irs.gov/pub/irs-prior/i1040sd--2021.pdf
