Recent example: https://parsley.mongodb.com/evergreen/rust_bson_fuzz_run_fuzzer_patch_431d4483856b18d1b8885d0b46a60be7f2eb2dee_6862b2bf41b36c00070bedce_25_06_30_15_52_34/1/task?bookmarks=0,2761

It's the raw_deserialize_utf8_lossy target, and it always fails with an error of the form range start index 16 out of range for slice of length 15 (although the indices vary).

The first commit that this failed on evergreen for is https://github.com/mongodb/bson-rust/commit/be2a10772e798a53b16938fb801d135c06c175bb, although it's a flaky failure so that's not 100% a smoking gun.