I think this represents the Chinese labs taking different approaches to the pressures of distillation.
Anthropic and OpenAI made it challenging to distill reasoning in a number of ways, including e.g. summarizing reasoning rather than displaying verbatim reasoning, and so on.
I suspect that Zai responded to this in GLM 5.3 primarily by leveraging exploits that work on models ~1-2 generations behind, but have been patched on more recent models (e.g., the dumb trick of "just giving it an external reasoning tool" that it ends up plugging its "actual unsummarized reasoning into"). The "native unsummarized reasoning tokens" in SOTA models are truly "caveman-like", because the leading labs have spent a LOT of recent effort on "token efficiency".
OTOH, I suspect that DeepSeek responded to this instead with a different strategy: They probably distilled more requests to the model to reason in prose with thinking off or low (and possibly settled for mixing in more thinking summaries from newer models, rather than settling for native reasoning from slightly older ones). This kind of "reasoning" is more verbose because it's an output trained for human eyes rather than being meant directly for model processing. The outcome of this could plausibly be a smarter model (since it's distilled from smarter models) that's more verbose because that's a tradeoff they decided when gathering the training data.