The current version has a critical security vulnerability (https://www.mozilla.org/en-US/security/advisories/mfsa2024-51/) but to fix it the new version compiled against libclang version 27 but Google decided to remove it from Android so the building pipeline needs to be adjusted.
There's a long discussion: https://gitlab.com/relan/fennecbuild/-/merge_requests/63 , about building the newer version
In the meanwhile the app is a security hazard.