For some reason, running af.diversity_stats uses an enormous amount of RAM (at least on Colab and Datalab). It crashes even my Pro sessions with 12GB of RAM. I tried:
af1.diversity_stats(
cohorts="cohort_admin2_year",
cohort_size=10,
region="3RL:1,000,000-2,000,000",
sample_query="country == 'Gabon'",
site_mask='funestus',
site_class="CDS_DEG_4"
)
and the same for Ghana (resp. 40 samples in one cohort and 31+29 in 2 cohorts) that fail in the same way.

Trying the same thing with Ag works fine (though, it also crashes due to RAM use if 'site_mask' is dropped). I tested on Gabon with 5 cohorts including 3 that have more than 60 samples.