Brian Tomasik wrote about it here. I should note that linking to this doesn't mean that I endorse what is written. It is written from a negative utilitarian perspective and with an assumption that invertebrate lives are net-negative, therefore it's good to reduce their population. Personally, I'm unconvinced that this assumption is correct, I think that we simply don't know. Also, I think it is likely that indirect effects of reducing invertebrate populations dominate direct effects. E.g., it seems that insect populations are already declining at an absurdly fast pace, and (pure speculation) this could maybe decrease the probability of the long-term survival of humanity in some way.

Brian also put AMF in his donation recommendations, seemingly for the sole reason that it "plausibly reduces invertebrate populations" (by increasing human population).

You might also be interested in a discussion about AMF's indirect effects here.

I found this post and the transitive links useful: https://forum.effectivealtruism.org/posts/guvsD78ZXhfCaT7SH/the-unproven-and-unprovable-case-for-net-wild-animal