Tractor Supply has many different brands of feed, milled in different places, ingredients sourced from different regions. If there is a problem with feed, it's isolated to specific brands and would likely be subject to a recall.
It's improbable that an issue with the feed would affect laying without also making them sick. Any other symptoms?
Like
@SueT was saying, winter laying breaks are normal for older hens.
If you haven't encountered this issue before then you had something different going on back then - most likely artificial lighting increasing the hens perceived daylight hours, perhaps even unintentional lighting.
Only a very low level is needed, so lights outside the coop on other buildings etc. can do it.