Backwards compatibility is supported for maintenance releases within a Long Term Support track, e.g. assets created using a Desktop instance running v.3.4.3 would be compatible with a Server instance running v.3.4.0. Backwards compatibility is not supported for Feature releases (i.e. v.3.5.x).
The v.3.4.x releases and v.3.5.x releases will be compatible with the next base LTS release (v.3.6.0).