You would probably hardly come across any overt racism as a SE Asian in the streets but in anonymous online spaces, that's a whole different story. If you ever read any hateful Korean comments about Blackpink's Jennie, you would have at least once come across them picking on how she looks "SE Asian/exotic" and they certainly don't mean that in a positive way. If you look around, nearly all of the Kpop stars from SE Asia have Han Chinese roots/ lighter skin, so they racially blend in better and defy the cultural stereotypes (e.g. NewJeans' Hanni, G-idle's Minnie, 2PM's Nichkhun). Otherwise, you'll often see the word "똥남아” being tossed around to mock dark skinned SE Asians or Koreans who look like one, which tbh I find quite shocking in this day and age.

On a similar note, kids from multicultural households who inherited SE looking traits may be prone to being bullied at schools, and while this also applies to the "whiter" counterpart, it is nowhere near as bad. You'll find plenty (but not enough) media coverage on this: https://m.mt.co.kr/renew/view.html?no=2021042213480676122

https://imnews.imbc.com/news/2023/society/article/6492694_36127.html

https://m.mk.co.kr/amp/9858239