Anecdotally:

I have watched a ~3 minute video on B12 availability somewhere within the past 6 months.

It entailed that B12 gets mainly produced by symbiotic plants and used to naturally be in humans' and plants' diets. According to the video due to the antibacterial and anti 'this that and the other' chemical treatments we treat our produce with, the B12 produced by the bacteria disappeared in our produce.

It absolutely impacted me hearing that (again, according to that video) the B12 in animals and their produce mostly gets added by supplements into their diets (since the plants we feed them don't contain the B12 vitamins anymore due to pesticides and such) which means (according to the video) most of the "natural" B12 in animals is chemically produced B12 and only B12 of plants which can live symbiotically with certain bacteria contain "natural" vitamin B12.