Found the issue and submitted a fix. The F-Droid build was failing because their prebuild sed commands were referencing code markers that no longer exist after the review code was refactored to Kotlin. The sed pattern was deleting from a start marker to the end of the file, wiping out most of the class.
I restructured the code so all Google Play review logic lives in a single file (InAppReviewHelper.kt) that F-Droid can replace with a no-op stub, instead of relying on fragile sed patterns. Submitted a merge request to the fdroiddata repo: https://gitlab.com/fdroid/fdroiddata/-/merge_requests/35892