Pre-approval is a budget, not a yes to the property you have found.
A pre-approval letter says the bank will lend you up to a certain amount, subject to the property being acceptable. Cross-leases with defects, unconsented work, very small apartments and some new builds can all change the bank's answer once it sees the actual address.
That is why a finance condition in your offer is still worth having even with pre-approval, and why your mortgage adviser and your lawyer need to be talking to each other from the start.
A free 15-minute call with a property lawyer who only works with first home buyers.