I am glad that you are saying that space does not bend at all. Yet gravity is only part of the story. The other part is motion.
The Milky Way's fastest motion is the one-dimensional direction it is moving in, away from where it all began, 13.8 billion years ago.
This motion is not based on gravity.
Once you recognize that gravity is not the one reason explaining all, then you can look for the mechanisms at work.
1. Milky Way's linear move through space not based on gravity
2. Milky Way's circular motion, gravity-based
3. Solar System's circular motion, gravity-based
4. Earth's spin, gravity-based
The Fastest Motion is seen with #1, the linear move through space.
This way, you should be able to spot what is going on mechanically when matter (the cesium clock, for instance) is moved away from the Earth's spin.
It will show that its material behavior changed due to the difference in position in A/ gravity and B/ motion.
The clock was of course involved in all four actions, but with its placement further away from Earth its behavior got changed; the influence of planet Earth was taken a step down, removed from the sum of actions.
If we review this in a mechanical manner, then the clock was more in touch with the other motions (and I focus particularly on #1, the fastest motion). The more exposed to #1 (through the diminishment of one or all others), the more the behavior changes.
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Something special is happening for Mercury because the spin of the Solar System means that the center is actually moving the least. The center of spins are always the slowest, or not moving in that spin at all.
It's like an eddy in the river.
Leaves can collect in an eddy (while nothing can collect in a whirlpool). We do see that confirmation with the Sun because we only have light-weighted matter here.
So, the Sun itself, mighty as it is, is not the greatest reality for the behavior of matter that is spinning around the Sun, in this case Mercury.
Mercury experiences a difference in its behavior compared to what the Newton model calculated because the closeness to the center of the Solar System spin was not included.
Do you see it?
We have again a diminishment of one of the gravitational realities, so the exposure to #1, the fastest motion (not based on gravity), becomes more important. The slowing in the center of the Solar System automatically means a greater purer exposure to #1, a change therefore in the behavior of matter.
It is a mechanical outcome, Alexandre.
We have matter, and matter exhibits gravitational properties of its own (and collectively).
And we have motion.
Together gravity and motion explain what is going on with matter.
