Subspace layer
A subspace layer is a region of subspace.

In 2372,  encountered Suspiria and learned of Exosia, which was described as a "subspace layer of pure thought and energy". ()

In 2375, Voyager became stuck on a subspace sandbar, which is a subspace layer in which the barrier between normal space and subspace is unstable. ()

In the same year, the "telepathic pitcher plant" entity appearing as a wormhole, sensed that Seven of Nine was immune to its manipulation. It convinced the crew of the Voyager, that Starfleet on the other side had asked to put her in stasis, because the wormhole passed through a layer of subspace monitored by the Borg and her neural transceiver might attract their attention. ()

de:Subraumschicht
layer