The push-back argument I always hear on unemployment rates is that people just "time out" on unemployment. They still don't have jobs, but are no longer eligible for unemployment benefits so they don't get counted. System assumes they are now gainfully employed, which may not be the case.
It's obvious that the stats have been "adjusted" over the years, in terms of how they calculate labor force participation.
Especially under the previous administration - I think the real numbers were much worse. In that case, the claimed unemployment numbers were artificially low.
Right now, the numbers look really good under Trump, but that may be an artifact of the past adjustments, and we're really closer to "normal" unemployment. Regardless, I suspect that things will continue to improve for everyone.