I get all my driftwood from a local pond i just soak them in boiling water for a few hours drain repeat then wipe down with a towel wash it under hot water n bam throw it in my tank..never no problems
It's tannins and will go away eventually with water changes and whenever it decides to stop leeching in to your water.You can take a rubbermaid tote,fill with water and let it leech there and do water changes until its done but no other way to avoid the leeching.Its gonna leech until its "done".
water changes help everything