I watched a documentary on DWTV about a similiar phenomena in Germany. There was a specific sort of bread, a cheap one, which stood fresh for two weeks if packed well. During the pandemic it suddenly stood fresh for NINE MONTHS. The finder of that bread was some sort of forensic specialist and because during the pandemic crime pretty much vanished he had too much time and explored that phenomena.

So, did they put more chemicals into the bread to keep it more fresh?

Actually, no. wholemeal bread stays due to the acid produced by the leavening during baking which is a natural process. Actually ALL bread stays in theory fresh "forever".

But. If it gets contaminated with fungus spores then those can slowly break up acids in the bread. Well, the final verdict was: Before the pandemic most bakers were so fucking dirty and contaminated that they pretty much only delivered fungus-contaminated bread. During the pandemic though the bakers were required to sanitize their work space and themselves a lot more thorough. And that made the bread free of fungus.

The forensic specialist has kept another bread for over three years now. It is as fresh as the first day. No chemicals involved, just wrapped airtight into a plastic foil.