"Therefore, a bitmap scan increments the pg_stat_all_indexes.idx_tup_read count(s) for the index(es) it uses, and it increments the pg_stat_all_tables.idx_tup_fetch count for the table, but it does not affect pg_stat_all_indexes.idx_tup_fetch."
There is repeated mentioning of pg_stat_all_indexes.idx_tup_fetch while I suppose one should read pg_stat_all_indexes.idx_scaninstead the second time. I.e. bitmap scans do not increment idx_scan.