I thought during 2015-2019, someone like John McDonnell, while I didn't agree with everything he said or did, really matured and grew into his shadow chancellor role and in front line politics (Corbyn and him while not feuding drifted apart from 2018 as he was clearly much more focused on actually trying to win power), while Abbott on the otherhand actually regressed and was completely out of her depth.
Of course this letter is inexcusable and goes way beyond her various blunders at shadow home secretary, and she deserved the swift sanctions that she received.