This makes me think that a new #3rd-party tag could be created and used, similar to how we use unsupported-install. For example, in the case of Dashboard New Posts statistics broken, there’s much to learn about debugging Discourse in general, but only a small part of the conversation is about the specific plugin causing the issue. I don’t think it would be ideal to move the entire conversation into the plugin’s topic, as this isn’t the place where I would look for examples on how to narrow down problems.
Therefore, I think keeping it in its own topic with a #3rd-party tag would make more sense. It might be better to place this in the support category rather than the bug category. That way, users can select a solution, and the topic will automatically close. In the bug category, a staff member would have to manually close it.
So, a topic could be created, replies would contain the steps to identify the cause. The post identifying it selected as the solution, the topic would be tagged with #3rd-party, and moved to another category if needed. Then the OP could notify the plugin/theme/component author by posting in the dedicated plugin/theme/component topic if they don’t already know. Though maybe even in that case, a post in the topic would be helpful for others having the same issue.