When you upgrade the main Twenty Twenty-Two theme from version 1.8 to version 1.9, the customizations you made within your child theme should remain intact. Child themes are designed to preserve customizations even when the parent theme is updated.However, it is always recommended to create a backup of your child theme before performing any major updates. This way, if there are any unexpected issues or conflicts after the update, you can restore your customizations from the backup.In most cases, minor theme updates like moving from version 1.8 to 1.9 should not affect the customizations made in the child theme, as long as the core structure of the theme remains consistent. It is good practice to review your child theme after the update to ensure that everything is working as expected and that your customizations are still applied correctly.If any issues arise after the update, you may need to troubleshoot and make adjustments to your child theme to accommodate any changes or new features introduced in version 1.9 of the Twenty Twenty-Two theme.