Tapping a catalog link in the mobile app leads you to the landing page of the catalog, and doesn’t apply the catalog filters included in the link.
There’s a lot of popular UGC items uploaded to my account before Roblox let us upload accessories to groups, and I need to be able to smoothly link back to those older items. Players can still visit a dedicated shopping experience, or manually type my username into the catalog filter, but I think a lot of people would get annoyed by that point and move on to something else.
This bug isn’t an issue on the Microsoft Store W10 app, which opens the correct catalog page with filters applied in my default browser.