While I agree the iPad Pro 10.5 should have iPadOS 18, it should be noted that the iPad 7th gen wasn't even released until after the iPad Pro 10.5 was discontinued.
The iPad Pro 10.5 was discontinued in early 2019, so by the time iPadOS 18 is released, it will have already been more than 5 years after it was discontinued.
It doesn't affect me much though, since I gave my iPad Pro 10.5 to my son a while ago, and I personally am using an 11" iPad Pro M4. My son won't care about iPadOS 18 at all. But I still wish the iPad Pro 10.5 would get iPadOS 18.