Another user recently reported invalid queries from their solar inverter (different branding to yours).
The query isn't for a valid domain, so even if it goes upstream from Pi-hole, it isn't really going anywhere. Unless it starts hammering your network non-stop it is probably not actually a problem.
If you want to make sure the malformed domain requests don't leave your network, you could enable dns.domainNeeded (in settings -> expert -> dns server)
Ask manufacturer what it's about
Wouldn't hurt to try.