I mean the fact she hid this all from every other angel is suspect, the fact she never bothered using any means to investigate despite having a magical crystal ball and the fact its implied Lucifer at least regularly talks to the Angels once a year and she never once explained herself (which like the fact there are diplomatic meetings with Lucifer at all make this stupid if he's supposedly responsible for a Hell uprising) about why the exterminations are happening really dampens any moral highground she has.
The show itself tries to frame Sera as flawed by pulling the card about all the innocent souls that were being slaughtered on her command, instead of the fact she's just dumb as bricks. Hell its implied she knows innocent souls are being killed with how she hid this information from all the other high level angels and feels guilty when Emily knows the truth, as though she knows she's doing something wrong.
Its kinda funny how Adam runs circles around her when writing and he's meant to be a more simple villain (since he just wants to do exterminations for the love of the game and possible revenge against Lucifer which makes more sense)
In essense, its this image
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