That is how IRS levies have always worked:
https://www.irs.gov/irm/part5/irm_05-011-004
5.11.4.2 (02-15-2018)
Holding Period
1. Under IRC 6332(c) a bank must wait 21 calendar days after a levy is served before surrendering the funds in the account (including interest thereon) held by the bank, subject to extension. On the next business day after the holding period expires, the bank must surrender the funds in the account, up to the amount of the levy. The depositor(s) can waive this waiting period. The bank will not surrender money that is subject to attachment or execution under judicial process. "Bank" includes credit unions, savings and loan associations, trust companies, and others described in IRC 408(n) and Treas. Reg. §301.6332–3(b).
2. During the holding period, a levy might be released, or the amount owed could decrease.
Note:
If the bank receives no release, it must surrender the funds in the account after the holding period. No additional notice is required.
3. Consider the holding period when deciding how long to project the accruals on a bank levy.