It would be more logical to create a new tournament for the new version, where testing could take place.
There may be certain criticisms of version 1.5 (this is inevitable), but overall, it is significantly better than version 1.4.2. The new interface features, for example – how did we even live without them before...? Or Jeb the mirror.
Therefore, a mass transition of all tournaments to version 1.5 is a historical inevitability, and if that's the case, why delay it?