After the upgrade to Koha 21.11, the "Add Patron" page has the card number field prefilled with the numeral one "1".
Hi Micheal, I think your problems is related to the koha-plugin-barcode-prefixer plugin, and not a problem in Koha. Kyle has provided a fix for the plugin: https://github.com/bywatersolutions/koha-plugin-barcode-prefixer/commit/9b27bbb57b3e513d368babcda9dc77b2b03ce2b2