https://www.heise.de/news/Bundesrat-stimmt-zu-E-Rechnungspflicht-fuer-Firmen-kommt-ab-2025-9663131.html

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.bundesfinanzministerium.de/Content/DE/Gesetzestexte/Gesetze_Gesetzesvorhaben/Abteilungen/Abteilung_IV/20_Legislaturperiode/2023-09-08-WtChancenG/Stellungnahme-01-Spitzenverbaende-der-Deutschen-Wirtschaft.pdf?__blob=publicationFile&v=2

https://www.dstv.de/wp-content/uploads/2023/10/BMF_2023-0922192-R.pdf