From 2027, all merchants are required to deliver invoices in one of the following formats:
Cross Industry Invoice (CII) and Universal Business Language (UBL) as well as Factur-X/ZUGFeRD
Simple PDF invoices without the embedded XML will no longer be permitted.
As a consequence, the EasyStore will no longer be usable for German customers if the corresponding formats are not supported by then.
https://www.dstv.de/wp-content/uploads/2023/10/BMF_2023-0922192-R.pdf