When Flight Recorder was open sourced with JDK 11 the syntax for the command line option -XX:StartFlightRecording was extended.

https://docs.oracle.com/en/java/javase/12/tools/java.html#GUID-3B1CE181-CD30-4178-9602-230B800D4FAE

Previously the syntax was:

 -XX:StartFlightRecording=parameter=value.

From JDK 11, the following syntax is also allowed.

-XX:StartFlightRecording:parameter=value

similar to unified logging (-Xlog:). It may make sense to call out that there are two ways, as there may be users with older releases and/or scripts that want to use the previous syntax.