This is not a legal ethics question because your landlord is not a lawyer. What does your lease say? If you don't understand your lease, take it to a general practice lawyer and ask for an opinion. It should not cost much. If you have no lease, your landlord can get rid of you for any reason or no reason.
You may want to consult with a lawyer regarding the Fair Debt Collection Practices Act. If it is a business debt, the Act may not apply so you will need to give all the appropriate information to a competent lawyer. Debt collectors have to follow specific rules about WHO they can talk to about your individual debt. Good luck.
Under the Fair Debt Collection Practices Act, there are rules as to who the creditor can discuss the debt with. However, this only applies to consumer debt, not business debt so it will depend on whether it is personal debt or business debt that is being collected.
There are many reasons why the creditor may need to notify the landlord; there may be collateral in the leased premised that may be foreclosed on and need access to remove. Without knowing more details, it is hard to say. You might want to consult with an attorney in your state.
The answer provided here does not constitute legal advice and should not be relied on as such. The attorney's response to your question is only offered for informational and educational purposes. No attorney-client relationship has been created. This attorney is licensed to practice in the state of NY only. For real legal advice, a licensed attorney with jurisdiction in your state should be consulted.