After hovering over the Radiant Remnant icon under the nameplate to see its tooltip all other tooltips will clip out of frame instead of clamping to the borders. Tested with Plumber as the only active AddOn to make sure that its not a compatibility error with another AddOn.

Before hovering over the icon (right side of the screenshot is the edge of the screen):

After:

Hi! It's been fixed in our latest update.
It appears Blizzard uses a different tooltip for nameplates (GameTooltip vs NamePlateTooltip, although they look identical), so we adapt to that.