Please provide details about this network share and the exact procedure you are following to access the sketches.
Due to a bug in the Eclipse Theia framework Arduino IDE 2.x is built on, opening sketches from UNC paths has never been supported by the IDE (including in 2.2.0):
However, you can open them from network drives. I just verified this still works fine for me even using Arduino IDE 2.3.0.
Please provide a detailed description of what you mean by "recognised".
It is not expected that the use of a different IDE version would cause this.
When people report things like this, what we often find is that the true cause is that different versions of the boards platform and/or library dependencies of the sketch are installed in the environments used by each version of the IDE.
I would be happy to investigate this problem, but I'd need more information to get started on that. I suggest you start by preparing a minimal sketch that compiles in Arduino IDE 1.x, but not in Arduino IDE 2.x. Once you have done that, post the sketch here as well as the full and exact text of the errors you get when compiling it with Arduino IDE 2.x.