You probably have "Smart Mode" enabled. Smart mode will automatically improve the quality of items until they are an upgrade for you, and then show you an estimated "rarity" for that item, e.g. high-titanforged items are extremely rare. You can then filter based on your desired rarity threshold.
You can also disable smart mode with the checkbox at the top of the list.
One of the main uses of the upgrade finder is picking which bosses to bonus roll on. You can't not have a chance to get titanforged gear when bonus rolling, so you would pretty much always want smart mode on for that use case.