Can someone please elaborate on this? What is the "reproducibility crisis" in this case?
In a nutshell, the crisis is that there is far more incentive to churn out a new publication/study than reproduce an existing one. So we have tons of studies that are the only one of its kind that have not been reproduced. The crisis part comes in where attempts to reproduce the results of these studies fail which throws into question the legitimacy of the entire field's publications.
So you can imagine how putting your faith into covid-19 related studies (such as effects of hydroxychloroquine) that were rushed and results not reproduced independently can result in problems down the road.
Science is probably the best tool we have for determining truth. However, it takes a long time and a lot of effort to converge on the truth and people put far more faith than they ought to in the results of fresh publications that have results they like (or fear).