I've solved it.Problem was in addressbook.acrodata I've deleted whole directory of "%appdata%\Adobe\Acrobat"Then manually updated AATL and EUTL list in Acrobat in Edit > Preferences > Trust Manager And it's validating signatures correctly now. Even it shows EUTL server in validated signature detail, before it showed only AATL.Probably some update of Acrobat Reader DC from last 2 months did this, because I have multiple computers with same problem.
I have opened your PDF in Acrobat Reader here and got a "Signed and all signatures are valid." I even updated Adobe Reader to the same version 2021.001.20155 and explicitly updated the trust list information.
An interesting difference to your screen shot, though: Here the certificate path is only displayed up to the intermediary qualified CA certificate, not the root CA certificate. This suffices as that intermediary CA certificate already is trusted by the AATL and/or EUTL.
Thus, it looks like this is not a general issue but one specific to your configuration. Have you or has your system administrator changed relevant trust settings in a way that the intermediary CA certificate is not trusted directly anymore but trust requires the root CA certificate?
Indeed, that root CA certificate in the Adobe Reader trust settings is associated with the policy requirements you see in your screen shot, i.e. 0.4.0.2042.1.2 (NCP+), 0.4.0.194112.1.2 (QCP-n-qscd), or 0.4.0.194112.1.3 (QCP-l-qscd). But the end entity certificate in your certificate chain only has the related policy 0.4.0.194112.1.0 (QCP-n). Thus, if trust is based on the root CA, that end entity certificate does not fulfill the associated policy requirements.