If you are ready to turn the units and "get to gettin" on the rehab side then I'd consult a local attorney but general giving a formal final notice to stop smoking in unit and that any damages or costs associated with remedying the unit are going to be billed to them. 

Using the word “mold” too soon can create unnecessary alarm and potential liability if the stain turns out to be mildew or another harmless substance.Once confirmed, landlords should hire a licensed mold remediation specialist to properly clean and document the repair.

Tight box, steady audits, clear remedies.

Yes I am working with my property management company closely to try and remedy this.

.❌ No more Collection Appeals Program❌ No more installment agreement negotiations❌ No more administrative remedies❌ No more Form 12277 lien releasesInstead you get:✅ Compelled depositions under Rule 69✅ Forced financial disclosure✅ Court-ordered payment plans✅ Contempt sanctions (including jail time)✅ Judgment liens that survive death and attach to inherited propertyThe estate goes from "problem solved" to "multi-generational nightmare" in 24 hours.

Focus on collateral first LTV, property condition, market rent, then the payor’s story and payment history; price yield to risk and prefer clear remedies with a recorded security instrument and servicer in place.

Or is there a remedy for basements that doesn't involve a new (correct) renovation?

Your only option is to sue for violating whatever contract you signed with whatever remedies are written into the agreement.

I’m curious if anyone else has encountered this, and if so, how did you remedy it?

These are common in small commercial, local bank loans, or bridge loans.Non-recourse loans: The lender’s only remedy is the property itself.