I wish Fizzy got to meet Flurry. It be sweet to see her motherly instincts.
On my headcannon, a Klingon sergeant known as Kloptern says very rude things about the Mane 6 and alicons including the Marer Do Well and Walking Dead incidents as well as Twylgith’s LessoN Zero, Queen Novo’s gem, and Cozy Glow errors. Fizzy was already angry, especially when the rogue mock a certain Wonderbolt and Flurtershy for being kind to ‘freaks’ and ‘primitives’ as well as Twylight. But the final straw was when the Klingon sergeant dare to call Flurry Heart an ugly, stupid mutant and threaten to send her to a freak show, hence why she punches him; a big way to show Fizzy cares for Flurry.