Automatically importing using statements causes a lot of issues because Rider adds using statements for incomplete statements, typos, etc. that are completely unnecessary. However, suggesting using imports in completion and allowing us to select one if desired is a very useful feature. Rider has both of these features, but one setting, "Show import items in basic completion," controls both. It should be possible to disable auto import of using statements without disabling suggested imports in completion.
Previous request was marked answered by saying to use the option to disable both features. This is not a satisfactory way to resolve this issue: https://rider-support.jetbrains.com/hc/en-us/community/posts/360000610444-Turning-off-auto-import-of-using-statements?input_string=Turning%20off%20auto%20import%20of%20using%20statements%20without