Others have already requested this, but it could be “Categories,” “Folders,” or “Tags.”
It doesn't have to be manual categorization—automatic sorting would be fine too.
I just want to categorize and organize them.

I know Vaults can be used for classification.
But Vaults aren't fundamentally designed to function like folders or categories.
And if you can only use 20 of them, Vaults are insufficient as a replacement for folders or categories.

When you have thousands of items, it's crucial to understand what services you're storing items on and how many you have.
If it's just login information fills, classification isn't necessary. Classification isn't for fills; it's useful for humans to manage things intuitively.

This issue has been discussed extensively, and honestly, I don't hold out hope for it being implemented in PP.
Therefore, I use Bitwarden and 1Password. (Though I do pay for PP...)

Those who reject the categorization feature can simply choose not to use it.
Implementing this feature won't make PP harder to use.
Rather, it would encourage users who like the categorization in Bitwarden or 1Password to switch to PP.
It's a case of “one size fits all.”

UI/UX might need some refinement, but users aren't always satisfied with simple beauty alone.

Please... please, I beg you, implement the categorization feature.
Until this feature is implemented, I won't use PP as my primary password manager.
Conversely, if this feature is implemented, I will use PP as my primary.
Many others likely feel the same way (I see this argument frequently).
How many users would actually leave PP because of this feature? Probably very few.
Weighing the “slight user abandonment” from implementing this feature against the “significant gain in new users” – there's simply no reason not to implement it.