Dr dear Dr: Is there any rationale behind the Polish Air Force sacrificing their fabulous Mig-29s for USAF F-18 Hornets?

None whatsoever, except the usual kind, the incredible generosity of the Poles. But yes, those Mig-29s are fabulous jet fighters and can easily outperform the F-18s. Cannot fathom why the Poles made the offer in the first place. Must be keen on USA branding. Sounds like a joke from that comedian fellow in America that got cancelled on Twitter some time ago this last year. But nope, totally agree, aerospatially more dynamic the Mig-29 looks like the F-14 Tomcat but it is mightily more manoeuvrable. Lovely Poles to consider sacrificing such planes and giving them to the Ukrainian Air Force. Nice people. Nice Air Force. Rock on Tigers.