As to actually acting on what they learn, within this context yeah that would be troubling.
iirc that was something more than infiltration. The FBI found an extremist loser who lived in a basement, egged him on, helped him network & gave him resources. Without them, he probably would have been thinking really hard about it, not much more.
https://www.cnn.com/2017/11/29/politics/aby-rayyan-fbi-terro...
It's how they found about Martin Luther King's affairs and what led them to write him a letter telling him to kill himself.
That (US domestic political groups, anyway) is their job, after all?
Given FBI Director Kash Patel is a Trump appointee, and I might even go so far as to say a Trump stooge, I think we have to assume that that is exactly what will happen.