In a direct communication, the source explained:

Indeed, there is a change in the presentation of central bank interest rates. The same series are disseminated, however, in one line, under a common title “Reserve requirements on zloty funds and foreign currency funds held in bank accounts, on funds received from issuance of securities”, where “zloty funds” cover zloty denominated demand and time deposits, and “foreign currency funds” – foreign currency denominated demand and time deposits.

In response, we have:

1. Archived the predecessors (1 January 1993 to 25 June 2018) by marking metadata as discontinued, and by segregating in the catalog
2. Created a replacement with start date 31 December 2010. Figures are percent per annum (% p.a.), not seasonally adjusted (NSA).

The series reside in the historical catalog (Poland » Financial » Monetary policy » Miscellaneous reserve requirement rates) and include, for example:

• IR%CBDZDEPUD.IPOL  = [DISCONTINUED] Interest Rates: Central Bank - Reserve Requirement - Zloty - Demand Deposits
• IR%CBTFCDEPUD.IPOL = [DISCONTINUED] Interest Rates: Central Bank - Reserve Requirement - Foreign Currency - Time Deposits
• IR%CBRSECUD.IPOL   = Interest rates: Reserve requirement - On zloty funds and foreign currency funds held in bank accounts; on funds received from issuance of securities, (% p.a., NSA)

Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.