This is a development policy suggestion.
T344498 broke mobile support for our self-hosted mediawiki when changing form 1.39.4 to 1.40.0.
We would like to request that Vector Legacy stays unchanged and only if really necessary have (only minor) changes.
Our argument: Vector Legacy has in its name that it's a legacy skin, not under active development. Most wikis which are still using it are probably either not doing active development or are otherwise relying on this skin staying the same. So we would argue Vector Legacy is the perfect skin to stay as is.
An alternative might be for us to rebase on Skin:Example, however re-inventing what Vector Legacy already does would be a high effort.