Found an impressive shot of the problem while surfing Reddit. If anyone is curious (shotouts to @Hiku), it looks like this, albeit the lines here are vertical:
So it also looks like the refurb unit Nintendo gave me has this way less noticeable than the other one, not to mention that the lines fade out after 5-15 minutes instead of 20 or more. So, I'll deal with that.
My bet with The_Liquid_Laser: I think the Switch won't surpass the PS2 as the best selling system of all time. If it does, I'll play a game of a list that The_Liquid_Laser will provide, I will have to play it for 50 hours or complete it, whatever comes first.