New printers can be okay. I don’t know of any specific problems with new printers except those ones with the ink subscription services. I’m saying my printer is old because it’s from another time. The only reason you’d isolate your networked printer in 2005 would be if you didn’t want other people to access your printer. Devices in your home automatically, deliberately making themselves worse on command from a cloud service was not a thing. The biggest danger with devices this old is that they probably have unpatched security vulnerabilities exploitable by anything else that gets on your network.

I have a VR headset from Facebook that is on its own VLAN because it defaults to randomizing its MAC address by default and this allowed it to bypass the firewall, phone home, and nonconsensually install new anti-features after being blocked because the setting got reset back to random when changing something. Recent LG TVs and other devices with worse preinstalled malware have been known to make requests to other devices on your network, but I’ve never heard of them using those other devices to get around network restrictions, at least not directly.