Koala Wallet was built from the ground up with security in mind, using all tools available to protect users from potential dangers of the web. But in the end, users are in charge, so some features can be turned off as long as the tradeoffs are known and understood. One of those features is screen capture protection.
What you'll be missing out on
By choosing to disable the feature, you will be making your wallet vulnerable to malware that records your screen and could compromise your Recovery Phrase security whenever it is shown. It also protects from accidental exposure from benign use, like streaming. Thieves who gain access to your Recovery Phrase can steal all funds from that account.
Other potential dangers
It's the default behavior of many gallery apps to immediately back up images to the cloud, unencrypted. Once a screenshot of your Recovery Phrase has been uploaded to services outside of your control, it is considered permanently compromised. Make sure you disable any such features before you screenshot sensitive information.
How to disable
Go to the Apps section and select "Security".
There turn off the switch "Screen capture protection". Read the warning, mark the checkbox and press the button "Disable protection".