Tell them that you are concerned because the trash is not disposed of, but placed on the property in a manner that the children can get into it and that there is so much pot smoking in the unit that it is very noticeable. 

Could we say nothing to the lender, allow month-to-month Tenant B to stay, and then hope that Tenant A voluntarily moves out at the end of his original lease without the lender realizing we failed to meet the 60-day move-in stipulation due to the circumstances?

Gun stores closed, pot shops open.

You can mention it but any action you'd like to take would be blunted by current eviction moratoriums, so I wouldn't stir the pot too much but perhaps worth mentioning in passing.

Be glad this tenant (who didn't follow the lease) is voluntarily leaving, and deduct any damages and/or lost rent until you find a replacement tenant that your state laws allow from their security deposit. 

A number of states deemed marijuana shops “essential” businesses and pot sales were up in recent weeks.

In general, our local economy is struggling with pot legalization, the black market has historically pumped lots of disposable cash into local businesses.

I've never put hot pots or cut directly on any countertop before and, technically, if a tenant causes damage, it comes out of their deposit.

I use large pots. 

Some people have different cleanliness standards and if its an issue, then get an old set of pots and pans from Goodwill and people need their own dishes, cups, and utensils.