Staining Acacia Wood Chairs

I need some help.
I have 6 acacia wood deck chairs to stain. The first one did not come out good and I not sure how to make it different. The chairs are over a year old and came with a stain that peeled and had little to no penetration. I sanded the chair completely, Used Defy Brightener (rinse, apply brightener, rinse again), dry to visible dryness (just barely), then same day applied Defy Extreme Stain for Hardwood (2 coats wet, within 20 mins, using a brush). The first coat absorbed great, the second coat was maybe too much to fully absorb and I had a few drips, but it overall looked really great. 3 days laying outside, and most of the surfaces facing the sky became very blotchy and dotted with dark marks that look almost like mold. Surfaces not facing the sky still look great. One unusual environmental factor is that the last few days have had a lot of smoke and ash from forest fires, and also fog.