You said it yourself! In politics, asking for favors often leads to corruption. Trump arrived in office already a corrupt person ethically and morally. Hakim Jeffries put it quite well in the first impeachment: “this for that" Do me a favor and just LOOK like you are investing Biden and I Trump will release the money Congress allocated to Ukraine- tit for tat, quid pro quo.

As to impeachment when the other party is in charge? Clever attempt at diversion. Obama never had impeachment because he never did anything to bring it on.

Your defense is of the indefensible. Trump is a man who has lied, cheated, sued, paid to be quiet, etc his entire life and as a wealthy white man never had to suffer any real consequences. He finally suffered one consequence- losing the election- which he did try by hook or crook, to reverse.