### Steps to reproduce 1. Post two messages in a short time in the main timeline 2. Click "Reply in thread" in the second message ### Outcome #### What did you expect? The timeline continuation is only modified on posting the first thread reply to the root message, not before. #### What happened instead? Timeline continuation is modified even before the thread is created. This is not reverted if the thread reply is cancelled. It only affects your current session. It's not persistent.  ### Operating system _No response_ ### Browser information _No response_ ### URL for webapp _No response_ ### Application version Element version: 479d4bf64d97-react-fbb8581f779e-js-34cfa511049e Olm version: 3.2.8 ### Homeserver _No response_ ### Will you send logs? No