They we make announcements in our Slack channel about this great tool they built that fixes some pain they had, without having done requirements gathering, or followed our internal RFC process, or even mentioned they were working on such a tool.
For example, there is a fleet of apps that I'm very familiar with and know what could be improved. There is a very old and ugly control panel that does the job and I have a long list of requirements for a well deserved rewrite. So today I log into it and it's a completely different app implemented from scratch that looks great but doesn't solve half of the issues we have. The control panel isn't "owned" by anyone, and it wasn't even me who created the first version of it. I took a look at the rewrite it's a complete garbage of a one-shot AI-generated app. And it's deployed in production and serving dozens of people (that were never informed of anything).
This is just a single example, there have been many.
How do you deal with this?