I get the same results as Carlos_Oliveras. With beta version 27.3.0 m3348 installed, there is no need to switch to Classic mode to record your actions, because clicking the + button in the Actions panel switches to Record mode and the tool tip for the + button tells you that.
If you click the + button in 27.3.0 m3348, you see the Actions panel change to the recording options shown in the picture below, including the Record button, the list of recorded steps we’ve been familiar with, and some enhancements. So recording is now part of the redesigned Actions panel.
Actions panel-27.3.0-m3348.jpg
Does that mean "Classic Actions" and recording your own - are considered a thing of the past? Why would Photoshop consider users recording their own actions no longer important? I am confused by this UI change.
By @Zebbler2
This is just how testing beta software works. Changes introduced at the beta stage (like the initial Actions panel upgrade and redesign) should not be assumed to represent their final form, and can change or be improved at any time as the work progresses and as they get feedback from us beta testers. It looks like Adobe always intended for the redesigned Actions panel to record, in other words they probably never intended to take away recording your own actions, but they probably delayed the re-implementation of recording until they validated the overall redesign that included the new capabilities.
Now we can test the re-introduced recording of actions, and if we public beta testers don’t report major problems with it, they will probably finalize it and graduate it out of beta to the normal release, and then it shouldn’t change much after that.