Is the SSID linked to your identity? Then it’s not GDPR.
Nonsense. “Personal data” is not just your identity. All data the relates to you is your personal data. That includes your home address. When your home address becomes aggregated with a unique MAC address, that MAC address also becomes personal data that relates to you.
And because the SSID does not include the string _optout_nomap, Google and Apple can use the SSID and MAC to track you and to keep tabs on where you relocate to so long as the Karcher radio moves with you.
Anyway, get a refund and stop complaining.
What EU country do you live in that you can get a refund on this basis (which according to you does not violate law)? Why do you think it would it be sensible to solve the problem for one person with respect to a manufactured product with likely tens or hundreds of thousands of consumers who are subject to the same abuse?