Add 4k, 6k, 8k, labels next to the clip titles in timeline for quick reference while editing.
Add a label next to each clip title in the timeline that shows if the clip is 4k, 6k, 8k, etc. Blank could be assumed 1080. Or 1080 could also be a label. This label system could also be nice for frame rate, i.e. 24p, 30p, 60p labels right there for quick reference as well.
Until this is a thing, you could change clip label colour within bins before placing on timeline. First sort the media in the bin by Video Info, colour desired clips according to resolution.