Yeah, Trump was big into genocide too, of the Yemenese. He personally vetoed a bipartisan resolution passed by congress to condemn the Saudis for their genocide in Yemen
But then we see the genocide of the Palestinians by Israel happening right now, and Biden not only enthusiastically reiterates his support for Israel but works to punishe anyone showing support and solidarity with the victims.
And that is why Biden is polling so low right now.