USCIS announced on February 24, 2021, that it reached the H-2B cap on February 12th. According to USCIS:
On Feb. 12, the number of beneficiaries for whom USCIS received petitions surpassed the total number of remaining H-2B visas available for the H-2B cap for the second half of FY 2021. In accordance with regulations, we determined it was necessary to use a computer-generated selection process intended to ensure the fair and orderly allocation of H-2B visa cap numbers available, without exceeding the FY 2021 cap. On Feb. 17, we conducted the selection process to randomly select petitions from those received on Feb. 12.
https://www.uscis.gov/news/alerts/h-2b-cap-reached-for-second-half-of-fy-2021
Cap-subject H-2B petitions filed for fiscal year 2021, with a start date before October 1, 2021, will be rejected. Some petitions are not subject to the cap, including H-2B extensions, fish roe processors, and workers in the CNMI and Guam.