B737 MAX 8 Captain reported an unstabilized approach when descending below the glide slope prior to runway threshold and the EGPWS annunciated a below glide slope warning. The warning continued during the flare and overrode the normal descent altitude EGPWS callouts and continued until landing.

Narrative

Landing Runway XXL in ZZZ; my intention was to put it down between the 1000 ft. and 1500 foot markings. At around 200 ft. AGL; I gradually ducked under the ILS G/S. I estimate I crossed the threshold around 50 ft. AGL. The EGPWS immediately started calling glide slope; glide slope. It seemed to trigger this caution very suddenly and kept activating. I estimate it triggered around six to eight times. It was so distracting that it caused me to add power; extend the flare; and double-check that I wasn't hearing too low gear. I continued; seeing that I was now really floating; approaching the final 3000 ft. touchdown zone painted stripes; when the EPGWS called its last glideslope; them immediately ten; and my mains touched down. The EPGWS never called 100; 50; or 30; because it kept repeating glide slope over and over again. It's like it got stuck in a loop. I do not think there was anything unusual with my descent to the runway. I estimate that it continued making the glide slope call even after I had passed the glide slope transmitter. Having landed ZZZ XXL hundreds of times; I have never had this happen. I would be curious if data could be obtained to reconstruct why the glideslope alert kept sounding. As stated; it was especially distracting during the flare. I tried finding the glideslope envelope in our flight manual but could not find it.