If the 'Programmer Art' resource pack is enabled, all the buttons in the menus are highlighted blue when hovering over them, however the accessibility button on the main menu is highlighted with a white border.
MC-174376 "Accessibility Settings" button in main page still has white border when using Programmer Art
MC-187082 When you load the programmer art recourse pack, the accessibility settings button still has the new button texture
MC-170469 Button highlight returns when using the programmer art resource pack, but text doesn't turn yellow
MC-169889 New textures aren't retroactively added to programmer art resource pack