Keep in mind that GLM-5.3 isn't GLM-5.3-Flash's "big brother" the way one might think. GLM-5.3-Flash is not GLM-5.3 scaled down. While GLM-5.3 is based on GLM-5.2, and "every gain comes from post-training" (https://z.ai/blog/glm-5.3), GLM-5.3-Flash uses a newly trained multimodal base model (https://z.ai/blog/glm-5.3-flash).