As said in the title, there is no way to disable the tooltips showing when hovering on the left side menu. See also https://forum.kde.org/viewtopic.php?f=17&t=175147
It's intentional that there's no "disable tooltips" setting that only affects System Settings; that would be overkill since other apps don't generally have this. However there is a systemwide setting to disable tooltips that isn't respected here. Fixing that is reasonable.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/systemsettings/-/merge_requests/153
Git commit bfe632e97a851540509fb2f54af21ea0511b46e6 by Nate Graham, on behalf of Anthony Hung. Committed on 24/06/2022 at 17:33. Pushed by ngraham into branch 'master'. Make sidebar tooltips respect the "Display informational tooltips" global setting FIXED-IN: 5.24.6 M +33 -0 sidebar/ToolTips/tooltipmanager.cpp M +2 -0 sidebar/ToolTips/tooltipmanager.h https://invent.kde.org/plasma/systemsettings/commit/bfe632e97a851540509fb2f54af21ea0511b46e6
Git commit aa827bd682b33b54828b8520b458a5b4a13c27c8 by Nate Graham, on behalf of Anthony Hung. Committed on 24/06/2022 at 17:45. Pushed by ngraham into branch 'Plasma/5.25'. Make sidebar tooltips respect the "Display informational tooltips" global setting FIXED-IN: 5.24.6 (cherry picked from commit bfe632e97a851540509fb2f54af21ea0511b46e6) M +33 -0 sidebar/ToolTips/tooltipmanager.cpp M +2 -0 sidebar/ToolTips/tooltipmanager.h https://invent.kde.org/plasma/systemsettings/commit/aa827bd682b33b54828b8520b458a5b4a13c27c8
Git commit 62de371709b847a5a6e8d96be55e12ac9e2e4170 by Nate Graham, on behalf of Anthony Hung. Committed on 24/06/2022 at 17:45. Pushed by ngraham into branch 'Plasma/5.24'. Make sidebar tooltips respect the "Display informational tooltips" global setting FIXED-IN: 5.24.6 (cherry picked from commit bfe632e97a851540509fb2f54af21ea0511b46e6) M +33 -0 sidebar/ToolTips/tooltipmanager.cpp M +2 -0 sidebar/ToolTips/tooltipmanager.h https://invent.kde.org/plasma/systemsettings/commit/62de371709b847a5a6e8d96be55e12ac9e2e4170