In T302627, @Krinkle helpfully added a script to French Wikipedia for logged in users that checks the skin preference and checks certain elements in the page (the Vector 2022 hamburger icon, the sidebar action "switch to old look" and the user avatar icon in the top right corner). For users were the skin was set to legacy Vector, and Vector 2022 elements were present in the page, an event was logged that was plotted into this graph:
The code suggests that at a rate of 1-6 page views a minute, a user of legacy Vector is receiving something that looks like modern Vector.
In T302627#7846955, @Krinkle poked concern at the "numerous unsafe service classes that Vector registers" as being the cause, however what is strange here, is that the hamburger icon is only rendered inside includes/templates/skin.mustache which can only be rendered if SkinVector22 is the skin class (this is set inside skin.json) and as far as I (@Jdlrobson) can see has nothing to do with the services.
We have had various reports (T288113, T300278, T303265, T305232, T305262) of strange rendering issues inside Vector. While some of them were almost certain related to the skin splitting of Vector, issues clearly still remain and questions unanswered.
Questions to answer
- How is it possible that a user preference can be set to 'vector' but the user sees modern Vector?
- Walkthrough feature management setup.