I honestly have no clue, these tasks are running on a google cloud linux platform. The only other possible relevant information I have is that I've been "merging" computers to keep the credit on the same "computer" - this also seems to result in tasks being marked abandoned. Another thing I noticed is that at least one of these tasks with arbitrary times was at one point marked abandoned, but suddenly became "completed" when I later refreshed the page.
Here's all the remaining tasks with the arbitrary time. The task that was at one point marked abandoned happened on or before October 24th: