Seeing Starlight constantly getting weaker and weaker from putting her anger in the bottle is just so uncomfortable for me to watch and it’s like she was going to collapse and fall into a coma! I’m all up for an episode of Glimmy controlling her anger and being more level headed, but this was a lousy start.
It being a very unhealthy thing to do was kinda the whole the point though. Starlight is a former super villain whose emotions (particularly anger) nearly ripped the timeline apart. So she went to an opposite extreme while trying to keep one of the few ponies that she considers a friend.
Plus, Starlight doesn’t exactly have a normal psyche. Being a former cult leader and willingness to destroy the timeline for revenge proves that, as well as the fact that she always seems to relate to other oddballs the most (Maud, Trixie, and Sunburst). For her to go around an emotional problem in a completely different way is standard for her, and in this case it backfired. As well plenty of other moments in her life (alongside the occasional moment of brilliance that is).