That debug line means that ClipboardFusion was notified of new content in the clipboard and so it proceeded to open the clipboard to read its content. When trying to do so, it found that another process was already reading the clipboard (AutoCtrl_2023.3.6.0.exe).
This situation is expected and all applications should be prepared to retry the operation if the clipboard is already being used.
Unfortunately, ClipboardFusion doesn't seem to be retrying; instead, it's apparently giving up after the first attempt. This is something that the developer could improve.
On the AutoControl side of things, the native component always reads the clipboard in order to provide the necessary data to several features of the extension, such as the <clipboard> placeholder or the "Clipbrd changes" event trigger or the clipboardChange scripting event.
One possible improvement here might be to avoid reading the clipboard if none of those features are being used.