If you are talking about the projections for potential rounds after August, these are projections

. They are based on the ratios of this round, these ratios can of course change, however if they stay the same then the projections become valid. If you are talking about something else, please point it out.
It's on that site. After this round according to that the distribution proprtions change.
As far as my eyes see and my math goes, I only see projections based on current ratios, mind that these ratios are also applied to what you get during each of the projected rounds. Can you please copy/paste (an example of) the info that says (makes you think) the distribution proportions will change?
... and it's compounding for you. That could be it.
Yep that's it

.
For instance, let's take September's projections, It says you'll have a total of
0.1375 GB for each BTC.
If you link 1 BTC now, you'll get
0.0625 GB after August's distribution. So you'll have 1 BTC +
0.0625 GB, if you hold for September's round, and provided the rules don't change, you'll get
0.0625 (for 1 BTC) +
0.0125 (for the
0.0625 you already have). After September's round, your GB balance will be
0.0625 +
0.0125 +
0.0625 =
0.1375. The same goes for the rest of the projected rounds.