For EU countries like Germany, invoices must be revision-safe and compliant with accounting regulations (e.g. GoBD).
Currently, invoices in HighLevel can be deleted and recreated using the same invoice number, which makes the system non-compliant for accounting use.
To make the invoice feature usable in Germany and other EU markets, the following would be required:
Invoice numbers must be immutable and never reusable
Invoices must not be deletable, only cancelable via credit note / cancellation invoice
All changes should be logged in an audit trail
Historical invoices must remain permanently accessible
This becomes especially important with VAT / Reverse Charge support for EU businesses, otherwise the invoice feature cannot be legally used for bookkeeping.