Source for this? I suspect you are talking about the UPU rates prior to the big jump in July 2020. Since that time international incoming deliveries have been highly profitable for the USPS. Also note that this was only ever an issue for packages under 2 kilos in weight. Postage for larger packages have always been set by market rates.With the US taxpayer paying the postage. Don't forget that part. We are paying the postage to move jobs out of the USA.
Even when the USPS was losing money on small incoming packages in the 2010s, they have always had a net profit over all international package shipments thanks to the charges for outgoing packages and larger incoming packages.