Apple doesn't support downgrading your iPad to an earlier version of iPadOS than your iPad is capable. That said, while iPadOS 18.7 remains signed and available for your iPad, you can restore this earlier version using DFU mode. While the process itself is both valid and officially recognised, you will need to research the process elsewhere.
Be aware that unless you have an archived backup of your iPad that was created prior to updating to iPadOS 26, you will lose all locally stored files and data from your iPad; an iPadOS backup cannot be restored to an earlier version than created (or updated) the backup.
Restoring an earlier version to workaround a current limitation will only have short-term benefit. Older versions of iPadOS will progressively lose update support and functional compatibility. App Developers are also likely to remove support for older versions over time.