A toolchain release can receive tooling updates and bug fixes without a new nRF Connect SDK release. These patched releases use a + suffix (for example, v3.4.0+1, v3.4.0+2) and have their own bundle IDs.
Multiple SDK versions can use the same base or patched toolchain. For example, the nRF Connect SDK v3.4.1 may use toolchain v3.4.0, then v3.4.0+1, and v3.4.0+2 as they are released.