Thanks for the warning. Did a rerun with the official OpenAI API directly and was able to reproduce the issue on those queries, so at least in this case, not OpenRouters fault. Also, shared them with Brian via Mail [0], hopefully useful to them.
Do occasionally cross-compare official with OpenRouter and have yet to encounter anything that wouldn't be replaced by run-to-run variance, but will keep an eye out for it, thanks for the warning. Have, especially with smaller labs, seen OpenRouter not support sometimes critical API features though, Inception Labs being an example. In fairness, the documentation of Inception Labs also had flaws like not noting certain API features being deprecated in their newest model.