I am not sure that is true. I think ships in the Star Trek universe warp subspace, not real space. We have seen examples of ships engaging their warp drive quite close to other stationary objects and not causing disruptive effects.
Not exactly. You have to warp normal space to access subspace. Subspace is a higher-dimensional realm, and the term "warp" refers to a topological distortion of 4D spacetime, such as distorting it into higher dimensions (like how gravity wells in science-museum demonstrations are depicted as heavy weights warping 3D pits into a 2D rubber sheet representing spacetime).
The warp model that NASA propulsion scientist Dr. Jesco von Puttkamer posited in his technical advisor's notes for
Star Trek: The Motion Picture was essentially the same one that physicist Miguel Alcubierre worked out with more mathematical rigor some 16 years later: the ship is encased in a bubble of flat spacetime that "surfs" on a propagating distortion of the surrounding spacetime, which can travel faster than light because there's no speed-of-light limit on how fast spacetime can expand or contract. Von Puttkamer used the term "subspace" (a term that TOS had used exclusively in the context of subspace radio) to refer to the pocket space within the warp field, but Rick Sternbach & Michael Okuda reinterpreted it for TNG as a hyperspace-like higher-dimensional realm that the warp bubble was "submerged" into as it propagated.
As for the lack of disruptive effects, it stands to reason that the gravity gradient of the warp field would have to drop off quickly enough on the inside that the ship would be undamaged, and thus the gradient on the outside would presumably drop off equally quickly. Something right on the edge of the warp bubble would probably be torn apart, but anything further away than the distance from the warp bubble to the ship's hull would be as unaffected as the ship itself.
Really, all that matters is that the spacetime distortion is extreme enough at the edge of the bubble, even if it flattens out quickly beyond that. Think of a microsingularity as an analogy -- as a black hole, it's an infinitely deep gravity well, but it's so tiny that you can be unaffected by it just a few feet away. It's only right up against it that you'd be in trouble.
One example would be Kirk stealing the Enterprise from Spacedock and engaging the warp drive right outside the doors. Spacedock was completely unaffected.
It was relatively close, but "right outside the doors" is an exaggeration:
https://movies.trekcore.com/gallery...1/chapter-05/st-tsfs-remaster-bluray-0516.jpg
Anyway, as I said, you can't necessarily take spaceship shots literally. There are cases where ships were shown in FX to be only a few ship-lengths apart when dialogue stated explicitly that they were thousands of kilometers apart. It stands to reason that the FX shots we see are not literal images, but artistic interpretations designed to convey events clearly to the audience, placing the ships far closer together, moving far more slowly, and being far more brightly lit than they realistically would be. (Also, you can see the matte lines around the miniatures in the shot above, all the more reason not to take it as literal photographic evidence. The Moon never looked quite right to me either.)