It depends entirely on whether conditions had been removed — that is the line that changes everything.
During the condition period the buyer generally has a contractual route out. If a condition is not satisfied or waived by its deadline, the contract typically ends and the deposit is ordinarily returned. That is what conditions are for, and it is not a breach.
Frustrating, but not a dispute. Your home returns to market and you continue.
This is different. Once conditions are waived the contract is firm, and a buyer who does not complete is in breach. The seller is not simply left without recourse.
What follows depends on the contract and the circumstances, but broadly a seller may look to the deposit, and may have claims beyond it — for example if the home ultimately sells for less, plus costs incurred in the interim. Pursuing anything beyond the deposit is a legal matter, and this is the point to involve a lawyer rather than rely on general information.
Deposits on Alberta residential transactions are ordinarily held in trust by a brokerage rather than by either party, which is a protection for both sides. It also means neither party can simply take it.
Where both agree on what should happen, the funds are released accordingly. Where they disagree, the brokerage cannot take sides — it holds the deposit until it has agreement from both, or a court direction. That can take time, which is one reason disputes over deposits are usually worth resolving commercially where possible.
The practical lesson: deposit size matters when you are choosing between offers. It is the part of a buyer's promise that has money behind it.
None of this is legal advice, and the answer for your situation depends on your contract. It is a conversation for your lawyer, and we will work alongside them.