Reported by @midnight finch
Bug Report: GPT-5.5 Thinking selected, but replies are generated by 5.4 Thinking
`Steps to Reproduce`
Open ChatGPT and manually select GPT-5.5 Thinking in the model picker, send a message in any conversation, including a newly created chat, Check the model shown for the reply.
`Expected Result`
Replies should be generated with GPT-5.5 Thinking.
`Actual Result`
Replies are generated by 5.4 Thinking.
`Environment`
ChatGPT iOS app on iPhone and iPad. Safari on iOS 26.4.