Help deciding to replace 12V battery

What are your thoughts on replacing the Prius 12v battery? Last replaced 70k miles ago / 5yr ago

Symptoms:
- poor smart key connection after sitting for the night (even after highway driving to charge the battery)
- Noticeably worse gas mileage despite all of the regular maintenance
- 12v battery charge is less than 11.6v with and without load first thing in the morning in accessory mode on display (apparently a sign of a dying battery)

Haven’t noticed other sx so far. I’m asking your opinion b/c it’ll be at least $200 regardless of brand. Rather not replace it if it’s not gonna help any

Maintenance I regularly perform:

• Oil change synthetic oil 5-7.5k miles
• Oil filter change
• Coolant recently replaced
• Cabin air filter
• Engine air filter
• Mass air flow sensor recently cleaned
• Tires recently replaced
• Tire pressure regularly checked
• Oil levels regularly checked

Highway HILLY mileage is regularly 40MPG. These are relatively large up and down hill 70MPH highways for 60 miles at a time. I drive then 3-4 days a week. They make up 90% of my miles nowadays. Could they really hamper my MPG that much? Odometer at 180,000 miles.