Animate 2020.
layer.getBlendModeAtFrame(frameIndex)
frameIndex - It is an integer that specifies absolute frame index.
A string value that specifies the blending mode applied at the particular frame.
Method; A string value that specifies the blending mode applied at the particular frame.
The following example displays the name of the blending mode applied at the first frame of the first layer in the Output panel:
an.trace(an.getDocumentDOM().getTimeline().layers[0].getBlendModeAtFrame(0));