wrt TikTok I assume the poll just asked what other platforms you are on, not if you are posting career related things on the platform. Most grad students are in their 20s and probably use TikTok for entertainment.

I’ve never seen anything as extreme as you describe, but when I took the GRE I met a guy kind of like this. After you finish the exam it gives you an estimate of your score, but your real scores are sent to you weeks later. On the way out some guy asked me how I did (fairly well but not 97% plus on anything). He was like “oh damn if you don’t get above 95% on math then you can’t go to grad school in STEM lol”. I asked him what he got in the reading and writing and he said <33% “but that isn’t important for grad school” lmao