Does a hybrid structure actually protect me from liabilities I don't know about yet?

Only partially, and it's important to be clear about exactly which part. A hybrid deal generally gives you asset-purchase-level protection for whichever piece of the business you structure as an asset purchase — undisclosed liabilities tied to that piece generally stay behind, the same as in any asset purchase. But for whatever piece you structure as a share purchase, you're still buying that corporation's full history, known and unknown, the same as you would in a standalone share deal.

The trap is assuming a hybrid structure somehow blends the two protections evenly across the whole transaction. It doesn't — it isolates the protection to the specific portion you route through an asset purchase, and leaves the rest exposed exactly as it would be otherwise. If the piece you're most worried about unknown liabilities in is the part you're structuring as a share purchase, the hybrid structure isn't actually addressing that risk.

The practical response is the same regardless of structure: representations, warranties, indemnities, and a holdback for the share-purchase portion, and a carefully drafted asset schedule for the rest. A business lawyer can confirm your protection actually lines up with where your real risk sits.