Since the apps are not vetted by Apple, they could contain keyloggers, ransomware, or code that steals your iCloud credentials, photos, or contacts.
In addition to certificates, the InvoxiPlayGames repo hosts critical tweaks to keep older devices usable: iOS Certificates cydia.invoxiplaygames.uk certificates
How do I install them? A: Add the repo in a package manager, install “Certificates” package, then go to Settings → General → VPN & Device Management → tap “Install” for the profile. Since the apps are not vetted by Apple,