How badly the UK did in the negotiations can be seen in the concessions won by the EU with the NI protocol. The actual trade deal covers goods where the UK has a large trade deficit and does not cover services at all.
Also the EU is starting to impose tariffs and checks on goods coming out of the UK, while the UK won't do the same for some time as their border control systems aren't ready and they're missing some 40 000 customs agents. So even as exporters are feeling the pain, the actual mangling of supply chains for british importers is still to come.
While the best case scenario for the EU would've been the UK staying in the customs union, with that option closed this is as good as it gets. There are no winners in Brexit, only relative losers.