Trump lies on twitter about the Postal Service claiming the Postal service is losing money on packages to Amazon and other companies. It is not true, by law, USPS is prohibited by law to lose money on competitive service deliveries. So when Amazon or another such company uses the USPS for the last mile of delivery, they have to pay the attributable cost that USPS is out. (If I understand right, pretty sure I do)
It is just one more example of Trump's pet peeves against the owner of Amazon who Trump considers the owner of the WP which is one the News companies he considers out to get him. All on account of Trump's hurt ego, he is advocating to let the USPS go down the tubes.
From the piece with the link below, I gather the administration wants USPS to exploit their advantage in rural areas to drive competition out of the market and make more profit to sustain their own cost (rather than depending on companies to give them an equal share of the cost); thus driving package delivery companies out of business.
In other words (again if I understand it right) what the USPS is not losing money as required by law, but they might not be making money, which I guess to Trump's mind, means they are losing money. That is not the way government works.
https://www.washingtonpost.com/politics/2020/04/27/trumps-claim-postal-service-loses-money-every-e-commerce-package-it-delivers/