- Large appliances are manufactured by other companies
- IKEA buys a lot of stuff instead of actually designing everything - so I'd expect them to buy something as simple as a USB charger
They're making a big bet on smart home stuff, which is why they're designing that kind of stuff more. They want to keep their customers coming back for smart home stuff so they can build an ecosystem, whereas they probably don't care about USB chargers nearly as much.
I'm guessing they're fine (they're probably testing it), but I highly doubt they're actually designing the USB chargers, and they're probably not buying from a known brand (price would be too high).
20W chargers are cheap from name brands (2 pack for ~€10), but 45W chargers aren't (like €20-30 for a basic 45W charger). So if they're selling 45W chargers for cheap, they're just likely rebranded stuff from a cheap manufacturer.