A lot of these things are continuations of previous trends too. The shimmering text effect is strongly reminiscent of skeleton UI, only repurposed for chat interfaces. As always, design is more continuous evolution than discrete shifts.

I actually like the shimmer effect, I think it’s preferable to almost all spinners.

If the agent is set up to properly show intent then this is better than spinners or exponentially decreasing loading bars.

As the saying goes: Slowly, then all at once.