Selecting text + copy adds the modelname to the clipboard

When you copy text by selecting it and pressing cmd+c, the model name gets appended to the text and shows up when you paste it.

How to reproduce:
1. Go to t3.chat and tell the AI to output “Hello, it's me”
2. Select the output text using the cursor and press cmd+c
3. Paste the text into an editor

→ Hello, it's me

GPT-5.3