27 January - International Holocaust Remembrance Day (all victims)

27 Nisan (Hebrew Calendar; Gregorian Date varies by year) - Yom HaShoah (Jewish victims)

2 August - Roma Genocide Remembrance Day (Roma/Sinti victims)

It’s never OK to challenge or downplay the suffering endured by the latter two groups, but if you specifically hassle Jews or Roma with your “but what about the X” bullshit on their own remembrance days, you are a special breed of asshole.