Ontario uses power of sale, not U.S.-style foreclosure. If the owner falls behind on the mortgage, the lender can force a sale. The lease does not evaporate.
Who gets the rent
Keep paying the landlord until you have written notice of a new payee. Verbal “stop paying” is how people get an N4 they did not need. If someone new claims the keys, ask for paper from the lender or lawyer.
Do not pay two places at once. Keep receipts.
Notices
A change-of-landlord letter is not an eviction. A later notice because the buyer wants the house for themselves has to follow Landlord and Tenant Board rules and timelines. Read dates. Keep a copy. Call the LTB if the wording is sludge.
Mistakes to skip
Stopping rent. Ignoring mail. Assuming the sale date is your move-out date. Power of sale is messy. Paying the named party and keeping the file is the boring way through it.
This is general information, not advice on a specific file.