The node states it should give +15% health leech after the third strike of Rive hits. This could either imply 15% flat leech or that it increases all Leech by 15%. However, neither of those effects is happening. As can be seen here, it goes from 0% to 2% leech, which wouldn’t work for either formula.
Upon further testing, it seems the node gives 1% leech with 2 points put in. I know leech rounds up on the character sheet, so it could be that the node is only applying 0.5% global leech per point rather than 5%, thus getting 1% from 2 points and 1.5% from 3, which is rounding up to 2%.