Trans people, LGBT people
Harris just said "I believe we should follow the law" when asked whether trans people should have access to gender-affirming care. This is leaving it to the states, which is essentially banning the existence of trans people in large segments of the country. She does not care about trans people or LGBT people as a whole.
Abortion rights
Roe was overturned under Biden, and Harris has not said she would stack the court or similar. She has said she would sign into law a bill passed by congress to restore reproductive freedom nationwide, but the dems almost certainly will not control the senate with a filibuster-proof majority, and even if they did they'd find some designated bad-guy who would turn coat to stop it (see: Joe Lieberman, Joe Manchin, Kyrsten Sinema). Harris will not do anything to protect abortion rights.
Ukraine
Which will lead to more Ukrainian deaths: the war coming to an end because US aid ceases, or a meatgrinder continuing for years which the Ukrainians have no chance of winning anyway? Which is more important: lines on a map, or actual human lives?
Black Lives Matter
Harris was a prosecutor. She's a fucking cop. She's VP of Joe "We have to fund the police!" Biden. She wants to build Trump's border wall. Harris does not care about black people.
Palestine
Harris fully supports the Israeli genocide of Palestinians. Her VP, Walz, has said that Israeli expansion (IE Greater Israel) is key to US interests. They may actually be to the right of Trump on this issue just because Trump doesn't have any actual political beliefs other than "make Trump richer", while Harris and the dems are rabid zionists.
Dem supporters have been holding their noses for 50+ years and voting for the "lesser evil". If that has brought us to this election, where your choice is between "genocide" and "genocide +", isn't it obvious that voting for the "lesser evil" just inevitably trends towards the greater evil over time? It is not a successful strategy at mitigating harm.