Depends. If it is stacked and well organized or set up as a camp I just go around it because it is likely a camp and the people will be back.

If it is stashed, well organized, but covered, perhaps camouflaged, or in a depression where it is less noticeable it is likely a cache. Some people leave a note that tells anyone who find it that it is a cache and someone is depending on it. Those I leave also.

In less traveled areas caches can be a good way to work things. You can preposition supplies for a longer hike later. In my experience the people who travel the deep swamps and distant woods tend to understand what is going on and to leave the supplies alone. Sort of backwoods courtesy. In more traveled areas you get a lot of duffers who don't know any better and they tend to be less thoughtful and considerate.

If I see some gear I might mark it on the map and visit on my way out. If it is still there it is a judgment call. In some cases it is clearly abandoned. In which case it is plunder or trash. In other cases it is less clear what is going on. In which case I leave it and try to make a point of mentioning it, possibly leaving the coordinates, with the local authority.

It is pretty easy to lose a cache. Often people will mention to the rangers or guides that they lost one, or assume it stolen, and it can be helpful for them to find out it is still there. coordinates or a marked map help.