Several recent M8 schedules have been replaced by transmissions in a phase-shift-keying mode known as PSK31. This mode is popular with hams, and can be heard daily on 14070 kHz. Many computer programs decode it. Digipan does a good job, and it's free.
If you hear a funny warble instead of the usual Morse in CW or MCW, this is what you have.
It is not known whether this signals a switch away from Morse code. Anything is possible with Cuban intelligence communications.