As per https://opensource.org/minutes20090304 this was rejected as redundant with Fair license https://opensource.org/licenses/Fair
Would you consider using Fair license or CC0 or X11 or Apache 2.0 instead?
https://www.gnu.org/licenses/license-list.html#WTFPL FSF recommends using X11 license or Apache 2.0
This is stopping gitlab from updating licensee which now include a dependency on reverse_markdown
https://gitlab.com/gitlab-org/gitaly/-/issues/2856#note_438114315