The bug was first found by Reddit users from the r/Windows11 subreddit, users reported issues with closing Task Manager where the users would click the “X” in the top right corner to close Task Manager but instead a second window/instance of Task Manager would open. The more you click the “X” button the more Task Manager windows open, which overtime will lead to degraded performance because Task Manager uses more RAM, and CPU resources.

The windows 11 update, KB5067036, notes state, the update includes a fix for Task Manager that resolves some apps not being grouped with their processes. As of writing Microsoft is not aware of this bug,

Thankfully Reddit users BNSoul has found a temporary fix. Individual Task Manager instances can be closed by clicking the “End task” button on the app instead of clicking the “X” button in the top right corner.