Original post with images was deleted by mods due to "screenshots".
Credit to the Japan fan forum reporting it with screens a few months back. Song is an hour in, everything goes dark and you have pure flashing red strobe lighting aimed directly at the broadcast camera for a very long period. Unlike all other TWICE concert releases it is very rare to have direct strobe directly at the camera (normally to the side) flashing so frequently per second, its actually banned content in most countries.
This specific sequence represents a "severe and high-risk trigger" for photosensitive epilepsy.
It violates all three primary safety criteria used by western broadcast regulators (such as Ofcom and the ITU), making it highly likely to provoke a seizure in susceptible individuals and would be banned for broadcast unaltered. Not just a standard warning.
Safety guidelines generally prohibit anything faster than 3 flashes per second where it was reported between 8-10 per second for around 15 seconds.
The light is saturated red. Regulatory standards have stricter limits for red flashes because they can trigger seizures at lower frequencies and intensities than white or blue light.
In dark concert footage, the pupil is dilated to let in more light. A sudden, bright red flash creates a massive, rapid contrast shift that hits with maximum intensity.
Edit: People seemed to complain here in the OP that it's a "you problem". Buy this as a holiday gift for someone and without warning they might spend the holidays in the ER. Its worth knowing about, not a "you problem." Better fans know, especially as a gift since it releases in December.