Do I still have whistleblower protection if I raised concerns before the sale happened?

Yes — protection against being punished for raising legitimate concerns doesn't expire just because the business you raised them at was later sold, and a new owner stepping into your employment generally can't be used as a fresh opportunity to retaliate for something that happened before the sale. If your concerns involved things like reporting unsafe working conditions or asserting your rights under employment standards law, the underlying protections against reprisal for that conduct travel with your continuous employment the same way your other entitlements do — a change in ownership isn't a reset button on protections you'd already earned.

That said, proving retaliation is always about connecting specific adverse treatment to the specific protected conduct, and a sale can genuinely complicate that picture, since a new owner may have entirely legitimate, unrelated reasons for organizational changes that happen to follow the sale.

If you're treated worse after the sale, demoted, cut in hours, pushed out, shortly after concerns you raised before the sale, that timing and connection is worth documenting carefully and getting looked at, rather than assuming a new owner gets a clean slate on what happened under the old one.