Halfy Monty FTP decrease

Hi I’ve been following the general road plan and got to the half monty mid plan test. I’ve followed the plan closely and felt good going into this.
My results however showed my MAP decreases by 2 and my ftp by 6. This was a surprise as on some of the rides my 20 min power has been higher than this.

I did have an issue at the end of the ramp with stopping the test and moving forward in the test. This has caused a drop in power as it took me a good minute to stop the ramp test. Could this have caused the ramp to record the wrong result?
I’ve included the power profile of the test.