I looked into users who have an empty up_value for up_property vector-limited-width and vector-limited-width-local-exception in mariadb on enwiki. Their user_touched timestamp in user table are within [20230202204750, 20230627212137 ]. It means they all had either logged in (not just mere visiting using an existing session), or modified user settings, or got promoted into new user groups between 2023-02-02 and 2023-06-27. [1] They likely have recently modified limited-width preference, resulting in an updated user_touched timestamp.

[1] ref: https://www.mediawiki.org/wiki/Manual:User_table#user_touched

Query

mysql:research@dbstore1003.eqiad.wmnet [enwiki]> SELECT min(user_touched), max(user_touched) from (select user_id, user_name, user_touched from user INNER JOIN user_properties on user_id=up_user  WHERE up_property IN ('vector-limited-width',    'vector-limited-width-local-exception' )  AND up_value='' ) AS t1;

Since we don't store vector-limited-width=1 it's safe to assume this is what is causing the empty values. The up_value of` 1 in the last row shouldn't be there and is probably due to data manipulation that might have converted an empty or null value into 1. Since the number is still insignificant at this point, I think it's fine to ignore it and focus on the Number of users who disabled limited-width stats for this analysis.

Is it possible these are coming from people who've set a global preference?
When I visit https://meta.wikimedia.org/wiki/Special:GlobalPreferences#mw-prefsection-rendering and enable the limited width preference globally, I'm noticing that clicking the button saves something to preferences but doesn't persist across page views.