This summary is not the rule. The rule text controls.
This rule says that lawyers cannot directly keep or use interest earned on client money they hold. If a lawyer's law firm holds client funds in a trust account and that money earns interest, the lawyer or their firm cannot pocket that interest for themselves.
Instead, any interest earned on these client funds must go through the Bar Foundation. The Bar Foundation then handles how that money gets used, usually for approved legal services or programs. This keeps lawyers from profiting off of money that belongs to their clients, even if it's just the interest sitting in an account.
For clients, this rule offers protection. It means your lawyer cannot secretly benefit from your money while it sits in their trust account. Any earnings that money generates go through a proper channel instead of straight into the lawyer's pocket.