Why is my iPad always typing capital and lowercase interchangeably?

Hello bronx03,

You'll want to start by making sure that both devices meet the system requirements for Sidecar to work.

Sidecar system requirements

Sidecar works with these devices and operating systems.

macOS Catalina or later

• MacBook Pro introduced in 2016 or later

• MacBook introduced in 2016 or later

• MacBook Air introduced in 2018 or later

• iMac introduced in 2017 or later, or iMac (Retina 5K, 27-inch, Late 2015)

• iMac Pro

• Mac mini introduced in 2018 or later

• Mac Pro introduced in 2019

• Mac Studio 

iPadOS 13 or later

• iPad Pro (all models)

• iPad (6th generation) or later

• iPad mini (5th generation) or later

• iPad Air (3rd generation) or later

Additional requirements

• Both devices must be signed in with the same Apple ID using two-factor authentication. Sidecar does not support Managed Apple IDs.

• To use Sidecar wirelessly, both devices must be within 10 meters (30 feet) of each other and have Bluetooth, Wi-Fi, and Handoff turned on. Your iPad must not be sharing its cellular connection and your Mac must not be sharing its internet connection.

• To use Sidecar over USB, your iPad must be set to trust your Mac.

Also, make sure both devices are signed in using the same Apple ID for iCloud. This will ensure all your settings stay the same across all your devices. However, keep in mind, if you 'want your keyboard, mouse, or trackpad to control your Mac and iPad, with the iPad showing its own Home Screen and apps rather than the desktop and apps of your Mac, use Universal Control instead.'

You can find all this information and more here: Use an iPad as a second display for a Mac - Apple Support. We hope this guidance helps you out.

Best wishes!