For Ladybird I think due to politics of the/a lead developer. I haven't looked into it and don't know it it is well deserved or silly. Just enough of a thing that I have seen it complained about before.

For Servo I have no clue why someone would downvote over that.

It's a bit of old news by this points so I had to go check, but basically ladybird dev is in the alt-right, qanon, trumpsucker end of the spectrum and the browser gets "pro-nazi funding" (eg.: Cloudflare), and more recently has started barfing "white replacement" mumbo jumbo.

At this point, Servo is a much better option than ladybird.