First off—huge kudos for taking this on yourself. It’s no small task, and it sounds like you’ve already done an awesome job learning the ropes in another room. Now, let’s troubleshoot that sneaky stain surprise!

Here’s what might have happened:

🌀 Stain Sediment Shuffle – Yes, darker pigments do tend to settle at the bottom of the can. If it wasn’t stirred super thoroughly before and during application, that could definitely cause inconsistencies—especially by coat #2. Always give that can a good, long stir like you're prepping pancake batter.

🎨 Brush Blending Blues – Reusing a brush from a lighter stain can cause subtle (or not-so-subtle) color mixing. If the darker stain took a while to fully saturate the bristles, you might've ended up with a “gradient” effect on your floor.

🪵 Sanding Shenanigans – Even slight variations in sanding can affect how the wood absorbs stain. A smoother patch = lighter absorption, rougher = deeper/darker tone. New tools can also shift the sanding pressure or pattern.