At https://www.mediawiki.org/wiki/Topic:Uny3l2uq8g8amp6w one user reports to get "the edit conflict viewer on every talk page I post on". Note this happened with the "inline" interface, before deploying the new "split" one.
Current status as of 2018-11-06:
- We don't know if more users are affected.
- We have not been able to reproduce the issue.
- We assume this is a core issue and has nothing to do with the TwoColConflict extension.
- If it is an issue with our extension, it's unlikely it will disappear with the planned T208319: Switch the TwoColConflict beta feature to its new look because both designs share code, and an issue as fundamental as the reported one is most likely in the shared part of the codebase.