Do you think it is a form of bribery for a charitable organization to offer special resources to people who donate larger sums of money?
No, I don’t think so. God rewards both sacrifice (Matt. 5:12) and performance (Luke 19:13-26). If incentivizing sacrifice is bribery, God is guilty. On the other hand, God measures our giving by the percentage we keep (Luke 21:3). Heaven’s reward for some small gifts will exceed that of some large gifts.