It’s great Panasonic has kept evolving DFD. This is not ‘rearing its ugly head’, rather their algorithm can decide when phase auto detection needs to lead and DFD takes a supporting role to increase the ‘confidence level’ to lock on targets and/or predict motion for the upcoming frames where phase autodetection is not ideal.
Sony also does not just use phase detection. Phase detection does not ‘understand’ the contents of an image the same way contrast detection does, and vice versa. Multiple technologies are uses in conjunction to provide the best performance possible.