Signature cause "invalidation" of previous sigs

[Bernd26717992y3mp]

I have a pdf with a valid signature (written with my own routines). Adobe says "valid".
If I add another signature, the Adobe acrobat (newest version) shows first sig invalid.
My verification says "valid", Foxit-Reader says "valid", the DSS Demonstration WebApp page from the EU says "valid".
So, what can cause the "invalid"-info in Adobe?

The pdf was created with libreoffice writer 7.4
The xref of the original pdf is not segmented
I didn't make any changes between the signatures
The first signature don´t use restrictions (DocMDP, etc), also the pdf didn't
If I click "view signed version" and the report I got some issues (see picture)

Can someone give me a hint/ where I need to look at?

Bernd

[MikelKlink]

Please share an example PDF that illustrates the issue, both before and after your second sigature.

(You already mentioned the obvious hints, so you are aware of the usual snares and pointing you to them won't help you.)

As you mention the newest version of Adobe Acrobat - do slightly older versions not declare the first signature invalid?