How does the sun experience a time dilation

Theme: Twin paradox and time dilation

hi, I have a question about the twin paradox.

The twin paradox says that: if a twin is waiting on earth and the other moves away from him, e.g. to the sun, stops there and comes back, the twin who was briefly at the sun is younger than the twin who has been waiting.

Now as I understand it: we call the waiting twin W and the one who makes the n detour to the sun is called A. While A is getting on his socks, the distance between A and W increases, which leads to the Information that originates from A arrives later at W and the information that originates from W arrives at A later, depending on the distance. When A has arrived at the sun, W would have to be about 8 minutes younger for A and vice versa. When A comes back to earth, the distance becomes smaller again and the two see each other faster. When they are on earth they should be exactly the same age again.
The time dilation, however, means - if I'm not mistaken - that the clocks pass more slowly for accelerated reference systems, and that is why A is younger than W. But since the acceleration is also only relative, W experiences the same from A's eyes Acceleration like A from the eyes of W. that is, if A comes back, A has remained younger for W, but W for A should also be younger. That would mean that both are the same age again?

times using the example of the proof of time dilation at the particle accelerator. If you bring a particle with a half-life of one second to almost the speed of light, the time dilation means that the particle only decays after, say, 5 seconds because the clock ticks more slowly for the accelerated particle. But it makes no difference whether the part moves in the accelerator or whether the accelerator and the whole world moves above the particle. does that mean that we also stay younger from the point of view of the particle?

and is there an explanation for why accelerated clocks pass more slowly? one approach of mine would be that it has something to do with the fact that acceleration is to be equated with gravity and thus that space-time expands. but I haven't really understood that either ...