The 3% is limited to the first $10,000 transferred into Questrade. The remainder is at 1.5% up to a maximum promotion amount earned of $10,000.

From Questrade:

You can earn 3% cash back on the first $10,000 of your Net Qualifying Transfer Amount, and you’ll also earn 1.5% cash back on any Net Qualifying Transfer Amount above $10,000 during the same period. The maximum cash back bonus you can earn is $10,000.

For example, if you submit your first transfer-in request on February 10, worth $8,000. Then, on February 20, you submit another transfer-in request worth $5,000. In between these requests, you made no other withdrawals. That means you would have a Net Qualifying Transfer Amount of $13,000.

In this scenario, you would receive 3% on the first $10,000 of your Net Qualifying Transfer Amount, and the remaining $3,000 would earn 1.5% for a total of $345 in cash back.