This is bugged for at least a year now. It's just an UI bug (damage, ward size, healing is increased on the right bar), so most people gave up complaining about it.
It's also a very odd bug, as I get it most of the time starting with the first bar swap after login, but sometimes it works as it should for hours. If I remember correctly, @ZOS_GinaBruno replied a long time ago that they were not able to reproduce the bug.
AzurasDaddy wrote: »Idk which platform OP is on, but I can confirm this is happening on Xbox NA