Hi, Paul!
In the old world, each user column used to be backed by a separate system render column that contained information about the column format settings. For example, each row in the system render column would store whether or not it’s multiselect, the selectable values formula, quick add, etc. This made it easier to handle formulaic properties (e.g. button label property), but that also meant that metadata was being stored for every single row in the table, even though a lot of it was redundant.
The column storage work consists of refactoring our codebase so that we can move the column settings into an object that is stored once on the user column. This allows us to get rid of the system render column in most cases.
We’ve made this update for people, lookup, select columns and are working through the remaining column types 