Thanks for reaching out.
?I suspect because this messaging has been added in WordPress 6.1.1. It would be prudent to add that this is not a Wordfence specific issue. It can happen with any plugin or theme (see this search for reference). If the job mentioned does not appear in your list of cron jobs any more, things should be fine so long as your scans are completing. This particular cron job mentioned just watches a running scan to ensure the scan finishes, and it does not need to be rescheduled when it ends. This looks like it could be caused by a race condition where two hits occurring at the same time are both trying to update cron jobs, which has been a long-standing issue in WordPress. It’s likely that one of the hits succeeded, and this error is the result of the second. Check to see if subsequent automatic scans are completing. If they are, you can likely ignore this error. If not you may have to set up manual crons. Most hosting companies have specific instructions on how to do this so googling the hosting company name and ‘wordpress manual cron’ will likely get you the instructions to do this.
Mia