There was literally a media freak out over the apointment of Amy Barrett because people thought trump was stacking the court in his favour. I don't know how true that is, but its clear that a significant portion of americans believe it (belief that the court is political is damaging in itself even if it wasn't true).

If court picks weren't political, political parties wouldn't fight to their last breath for them.

Most judges actually are non-partisan-decide-based-on-law type. But they simply are not favoured.

Consider that sanders made it a litmus test for his supreme court nominees to overrule an unpopular court decision. Most judges would avoid at a politician demanding this, as it defeats the purpose of a judiciary.