There's a lot of categories, no filtering, erroneous gear placement, and several other issues with the collections page, like entirely separate categories for just 1-5 weapons (until years later).
Just a suggestion: condense the number of categories and clean up the appearance.
For Primary Ammo, categories could look like this:
Automatic Weapons
Burst Weapons
Precision Weapons
Within each category, weapon types are denoted by a banner at the top of each page, such as "Auto Rifles", or "Submachine Guns" (maybe include rapid-fire frames such as sidearms and scout rifles too) within the "Automatic Weapons" classification.
Special Ammo categories could look like this:
Automatic Weapons
Close Quarters Weapons
Explosive / Launcher Weapons
Precision Weapons
...and Heavy Ammo categories could look like this:
Automatic Weapons
Close Quarters (Melee) Weapons
Launchers
Precision Weapons
All gear would automatically filter from newest to oldest within their respective categories, and each subcategory should be selectable via tabs on the side of each page.
Finally, I'd say remove the arbitrary "cannot reacquire randomized gear", since collections gear has static, curated rolls. And, maybe create a separate "leveling" category for weapons.
Now for armor, I'd organize it into categories like so:
PvE
PvP
Gambit
Endgame
Leveling
Universal Ornaments
subcategories could look like this:
PvE:
"Vanguard", "Pinnacle", "World", "Seasonal", "Events", "Other"
PvP:
"Crucible", "Iron Banner", "Trials"
The rest are self-explanatory.
Just a thought, I know none of this will happen though.