It seems to me that in 24thC fictional physics, a lot of high energy phenomena have subspace effects, even if there's no obvious subspace involvement from the point of view of real 20thC physics.
Wormholes and other nifty spacetime disturbances are definitely linked to subspace.
When Praxis exploded in ST:VI, a huge subspace shockwave reached Excelsior minutes after it occurred, clearly travelling at superluminal speeds and apparently interacting with the subspace systems on board the ship. I wonder if a 'natural' inert body such as a planet would have been affected - I suspect not. Likewise Excelsior may have been able to ride out the shockwave if they pulled the plug on all their subspace tech immediately - but this may be difficult to achieve and things may need time to spin down, so it may be better to leave the shields up and running.
Subspace shockwaves are also emitted by Supernovae - at least the ones set off during the Q civil war - but the crew of Voyager didn't seem to find it unusual that something like a star exploding was producing a subspace effect.
So anyway, my suggestion would be that most things that happen in normal space have coupled subspace effects. Higher energy processes have more of a subspace component than say, a lightbulb. Something like a Warp core on board a ship may general a subspace field just because it's a high energy reactor - not a useful subspace field that could be used to move the ship - but simply a result of large numbers of particle annihilations in a small area creating a high enough energy state to 'punch through' to the subspace domain.
This is detectable to 24thC sensors, but not to us, and doesn't have much of an effect on anything else in the normal universe except things that also have exotic subspace properties - such as the tear created by the Son'a subspace weapon in Insurrection, that precipitated the ejection of the warp core, or indeed most of the other subspace-enabled tech on the ship.
Just my two cents, anyway..