As a Roblox user, the Avatar page is a frustration with huge inventories that cannot load everything if they are quick enough to try to scroll through it. Hence the frequently found funky error within the console of code 429.
The case occurs more often when attempting to find an ancient junk within your inventory, but less frequently for brand-new purchases.
Had this same issue the other day when I tried to look at my older items to see which antlers I owned.
Many times it would flat out refuse to load anything, so I’d have to reload the page to load more pages, but eventually it threw me an error, “Failed to load assets list.”, and completely stalled the use of the avatar page for some time.
Do note, I am using Roblox Plus (R+) for the search bar feature, but this happens regardless of whether or not third party extensions are enabled.