A low-rarity item disappears from view after a settings change. Did the game remove it, stop displaying its label or decide not to collect it automatically? A menu called a loot filter can affect different parts of the experience, depending on the game.
Read the action described by the setting
Distinguish display rules from pickup rules. One option may hide labels on the ground; another may change automatic collection. A separate inventory option might sort, salvage or sell items. Do not assume they are interchangeable because each uses a rarity threshold.
Consult the current in-game explanation or official documentation for the title and version you are using. This is a checking method, not a claim that every game offers all these controls.
Test with an item you can afford to ignore
In an ordinary safe practice situation, observe one low-value item before and after changing a single setting. Check whether its label remains visible, whether manual pickup is possible and whether it appears in the inventory. Avoid using a unique quest reward as your first experiment.
For an invented game, setting the display filter to rare might hide common-item labels while leaving the objects available through a temporary show-all control. In another game, a collection threshold might leave those items behind. The same informal phrase would describe two different behaviours.
Keep exceptions visible
Look for rules affecting crafting materials, currency, quest objects or items with unusual properties. A rarity colour may not describe every reason you want an item. Check whether custom exceptions are supported before assuming a broad filter preserves everything important.
After a major update or a switch between characters, verify whether the setting persists and applies at account or character level. Save a brief note of the intended configuration if the game makes it difficult to reconstruct.
A useful filter reduces distractions while preserving the information and collection behaviour you want. Understanding what it changes is more valuable than selecting the most restrictive option and discovering later that you misunderstood where the missing items went.