Knowledge is under attack from several fronts at once. In science itself, it is due to corporate corruption and the inherent bias toward interesting but possibly false results. There was that paper about how most scientific findings are false.
In social science, there is a replicability crisis in social psychology and various forms of p-hacking and statistical overstatements. Then there are entire fields that just don't seem that rigorous in the first place, the typical things people look down on like management studies and education. Economics is corrupt because of its upholding of the economic status quo. The humanities have their own well-known problems.
What all these things have in common is that institutions are self-perpetuating, and that there are greater incentives for various stake-holders in having the system we have than in having a system guaranteed to produce a better variety of knowledge. Sturgeon's Law would say that only 10% of everything is going to be of value, so in order to have the 10%, we need to reconcile ourselves to the 90% of crap. We can't just cut out the 90% because then we wouldn't have enough critical mass to even keep going institutionally.