There is a better middle ground here by saying the company that made it may not have known, but nation state threat actors most likely do.
When you see actors at this level set up manufacturing thousands of explosive filled devices at very high production quality, inserting some compromised things like printers or routers in a company network wouldn't be and shouldn't be a surprise.
If the nation state actors did intentionally backdoor it, then they would have wanted to make it look like incompetence. Here’s a link to the Simple Sabotage Field Manual from the US. It worked well in occupied Europe during WWII: