Does anybody know what datetime format works when querying with REST API? I've tried 

q=lastModifiedDate ON_OR_AFTER "2021-01-15T11:11:00Z"

 and 

?q=lastModifiedDate ON_OR_AFTER "15/01/2021 11:24:00"

 . Both return 400 error.

Invalid search query. Detailed unprocessed description follows. Search error occurred: Parse of date/time \"2021-01-15T11:11:00.000Z\" failed with date format \"d/M/yy\" in time zone America/Los_Angeles\nCaused by:\n\tjava.text.

It tells you in the error message...

with date format \"d/M/yy\"