That linked thread is old. Old info is not often updated, especially when it is not the documentation and there are multiple threads. The reply you linked was a workaround that was not a supported feature and was broken for a more important, supported feature. A new feature to provide a proper solution will be in the next version 23.11 due in a few days.
Shotcut is a video editor and not dedicated crop tool. Video editing usually involves multiple items. In that context it is a bad idea to automatically change the canvas (output) size based on the crop of one item because the crop for item A should not be automatically be applied to item B. As a result, item B’s aspect ratio would no longer match the canvas and black bars will be added to it. Also, crop can be used in different ways for different reasons in a multi-item video composition. Maybe the video you want to crop is overlaid atop another video. Maybe you really do want to add black bars after removing some bad edges to output in a standard aspect ratio.
I understand that working with different videos with different resolutions and different aspect ratios can become a nightmare.
However, I usually just work with single videos, that I cut together a bit. For this simple use case, can I expect the crop filter to work just fine in the coming version?
If not, can you recommend a tool to crop the video? The only one I have used so far is avidemux. I’m also worried about degrading video quality, if I use a bunch of different tools, each encoding the video anew. That’s why I would prefer to do everything with one single tool and one single encoding process.