You lose more points at lower rank tiers. It’s relative to the 20k total and the fact only a certain percentage of players can be in each given rank.
You lost 6k but look at how much you stood to gain, about the same. The more you go up the values you gain and lose become less, if you go down it’s the opposite.
Around Gold to Onyx values are between 500-100 in terms of gain/loss.
Diamond + the values are like 70.
D3 and Masters it’s around 10-30 on average ( you can gain more than the here if you perform exceptionally well, just like any other rank ofc).
Losing a 100-200 in Diamond is about the equivalent to this. That could be the difference of a tier because D1 doesn’t start till 19400 or so and at that point there’s only 600 points left in the system between Masters and the other D tiers.
Point is, it’s based on what skill group you’re currently in relative to how much points are left to be gained. (20K)
The higher you go up the system places more expectations on your performance relative to however everyone else is performing at and below your skill group. At lower ranks the system can be very liberal with the points because the expectations for someone perceived to be in the bottom/middle percent of players aren’t high.
So if you perform well you will gain a ton of points until it moves you to a skill group where the performance expectations meet whatever skill level you’re at but the amount you gain or lose from that point is based on what’s left.