When shooting at higher iso (800 and above) and underexposing, i get this magenta band at the lower side of image, that becomes very visible if i increase the exposure in post. Even if i don't increase the exposure in post, it's slightly visible. When shooting at low iso, or high iso but properly exposing in camera, this doesn't happen, even if it increase exposure in ps afterwards.

What is this defect called? I only remember seeing one anon referring to this some time ago, saying that Nikons are worse at this than Canons, i never heard any youtuber talk about this.