Monkbot task 15 is a simple task that replaces {{xx icon}} templates with {{in lang|xx}}; Monkbot never does general fixes. After 50k-ish good edits an editor halted monkbot with a post to its talk page. See its contributions page:
- started blanking here; first bad edit at 20:26, 30 December 2019
- task was halted here; last bad edit at 20:47, 30 December 2019
Before being halted, task 15 blanked about 160 articles.
After the task was halted, I rolled back all of the bad edits; closed the instance of awb that was running the bot; restarted awb, restarted the bot task. The first 160-ish bot edits after the task was restarted are those articles that were blanked; none of them were blanked a second time.
I'm pretty sure that it isn't this task; I have seen this happen before on other tasks doing wholly different jobs. The single thing that is the same is that I have allowed awb to run for long periods of time without restarting. If there is a time limit that exists, perhaps awb should require a restart when that limit is reached. Perhaps awb can detect when it is blanking a page and halt with an appropriate message.