Has anyone seen this in an 8 year old Bernedoodle?

Over the past year our dog has changed quite a bit and we’re trying to understand what could be going on.

Symptoms:
• Excessive drooling
• Eats poorly / less interest in food
• No longer listens at home like she used to
• Often has a blank or distant stare
• No longer asks to go outside to pee (we now have to bring her out, and she will hold it for a very long time)

Background:
• No change in environment
• Blood work came back normal, vet says she is physically healthy
• All of this started within the last year

Our vet is hesitant to go further with expensive testing unless it’s likely to change treatment, as it may be something degenerative or not really treatable.

We’re trying to understand if this could be canine cognitive dysfunction, a neurological issue, pain, or something else people have seen before with similar symptoms.

Any experiences or advice appreciated.