There is an initiative in progress to update the general icon set (M229) to better align to [[ https://wikimedia.github.io/WikimediaUI-Style-Guide/ | the design guidelines ]].
Since the icons used for notifications, reuse several of the concepts defined in the general icons, we need to update the notification icons to match the new style. That will also solve the current inconsistency where icons based on the speech bubble shape point to different directions (T161330).
An initial proposal for adjustment is shown below. Icons marked as "reused" are existing icons from the general repo.