The input for this function is supposed to be a list containing single word strings, as in all other test cases. But in one of the test cases the single string in the list is a string of space-separated words.
I submitted a pull request but it was automatically closed with the suggestion to make a forum post here instead.
This is the pull request: Change anagram test case input by olapokon · Pull Request #169 · exercism/vimscript · GitHub
Thanks for the PR. Could you maybe open an issue at GitHub - exercism/problem-specifications: Shared metadata for exercism exercises. instead, as that is the place that has the source for this test: https://github.com/exercism/problem-specifications/blob/main/exercises/anagram/canonical-data.json
I made another PR in that repository Change anagram test case input by olapokon · Pull Request #2314 · exercism/problem-specifications · GitHub
Ah sorry, didn’t realize you said open an issue instead.