Two different rules
A purchase restriction stops the agent from buying an item on the marketplace. A shipping restriction stops a carrier from carrying it. They are enforced by different parties and change on different schedules, which is why an item can be buyable but not shippable.
Why brands get restricted
Marketplace takedowns, carrier prohibited-item lists and destination customs rules. A brand may be blocked on one line to one country and fine everywhere else. Blanket “banned brand” lists on forums are usually out of date.
What to do at checkout
If the order is refused, read the reason: “item prohibited”, “seller cannot ship” and “line restriction” mean three different next steps. Ask support which line accepts the category, or choose a different seller. Do not re-order the same item five times hoping the system changes its mind.
Design around it
Build the haul from categories you know ship to your country, then add the risky item last. That way a refusal costs one row, not the whole parcel.
Quick answers
Is there an official banned-brand list?
Not a stable public one. Restrictions are per marketplace, carrier and destination, and they change. Ask support for your specific item and country.
Can I ship a restricted item as something else?
No. Misdeclaring a restricted item is how parcels get seized and accounts get closed.