After months and months of complaints from the SEO community, Danny Sullivan from Google said the cache bug should be fixed soon. He posted on Twitter saying "We're aware of this and expect it will be corrected soon. "It has no impact on indexing. We have fresher versions indexed," he added.
The date in the cache for most sites is around a month old and people have been complaining about this for a few months now. Google is spending more time telling webmasters and SEOs to not worry about it then to actually just fix the bug.
So it looks like Google is putting a resource on this bug to fix "soon."
We're aware of this and expect it will be corrected soon. It has no impact on indexing. We have fresher versions indexed.
— Danny Sullivan (@dannysullivan) May 14, 2019
When is soon? I don't know, but as of this morning it is still not fixed.
Forum discussion at Twitter.