Although the TARMS system indicates that it is ZiG compliant, the currency dropdowns reflect USD and ZWL.
Note that where it says ZWL this refers to ZiG. So, if your 2023 return was in ZWL you must convert to ZiG. Put another way, where you see ZWL replace it with ZiG. Do not file your returns (even backdated ones) in ZWL and expect ZIMRA to convert it for you. They will not