Grout is curing too dark

I installed some Hakatai mosaic sheet tile, and to test a grout color, I grouted a small 1 sq ft. Area with the un-sanded grout we had selected. Since we liked it after it cured for a couple days, I grouted the rest of this tub surround with the same grout (from the same bag, the only bag I have). However, this application cured much lighter than the small area where I had done the test. So, I removed the grout from the test area, and mixed up some of the same grout (still from the same bag), and mixed it using the same paddle/drill in a bucket. I mixed more than I needed to try to make sure that the mix was as similar as possible to the batch that dried more lightly. However, the test area again cured to be much too darker. It has been two weeks now, and no change. Is there something different I can try doing to get the grout to lighten like it did all over the rest of the tub surround? TIA

One very important step I see left out here is dry mixing the grout to make sure all the pigment gets evenly re-destributed.

Beyond that you have all the other things that can make multiple mixes cure at different shades.

Providing you didn't seal the grout yet, your probably best to use a grout colorant at this point. Cutting out and regrouting the area is no guarantee it will be the same shade as the other wall if you didn't dry mix first and comparing the existing lighter cured grout to a lighter shade on that grout company's color chart is a hot in the dark that it will work. If you test out that option, be sure to dry mix first and give the grout several days of cure time in the test area.

Thanks. I will give those ideas a try