@Mark Hindley:

What does

apt-cache policy libldap-2.4-2:i386 libvulkan1:i386

produce?

|$ apt-cache policy libldap-2.4-2:i386 libvulkan1:i386||
||libldap-2.4-2:i386:||
||  Installed: (none)||
||  Candidate: 2.4.57+dfsg-3+deb11u1||
||  Version table:||
||     2.4.59+dfsg-1~bpo11+1 100||
||        100 http://deb.devuan.org/merged chimaera-backports/main i386
Packages||
||     2.4.57+dfsg-3+deb11u1 500||
||        500 http://deb.devuan.org/merged chimaera/main i386 Packages||
||        500 http://deb.devuan.org/merged chimaera-security/main i386
Packages||
||libvulkan1:i386:||
||  Installed: (none)||
||  Candidate: 1.2.162.0-1||
||  Version table:||
||     1.3.224.0-1~bpo11+1 100||
||        100 http://deb.devuan.org/merged chimaera-backports/main i386
Packages||
||     1.2.162.0-1 500||
||        500 http://deb.devuan.org/merged chimaera/main i386 Packages|

- AK