iPhone 13 Pro Max keyboard switching to other keyboards despite uninstalling them

My iPhone 13 Pro Max has been experiencing malfunctioning keyboard. While typing on any app, the keyboard switches abruptly from my default SwiftKey keyboard to other keyboards. Even when I uninstalled every keyboard on the phone but my SwiftKey keyboard, the issue still persists. What have reset my phone and the issue is still unresolved. What should I do?

[Re-Titled By Moderator]