Wow, this set up really has broken you...
I often find when a scape has run out of control
Not quite that drastic really, it wasn’t blasted at the end, just annoying:

Kind of like having something stuck between your teeth that you can’t get out… So took my hands to it:

And now the problem is much improved:

😂 😆 😝
Seriously though, the complete unknown timescale for that wood to stop leaching was the deal breaker. They were large and substantial enough bits of wood to raise alarm bells. The particular pieces of wood in question smelled stagnant when removed. Others just smelled like wet driftwood which was interesting. Lends weight to @Witcher ’s proposition:
I know from other threads you're plant keeper with quite rigoristic approach so wouldn't believe it's something about the water, there is definitely an abundance of algae spores in the wood (plus very likely wood mass is being perfect condition for their growth regardless of what's in the water - maybe it was previously laying in the water containing all the necessary ferts and other rubbish algae needs and had soaked what algae need ).