LTV - some can see enabled, some says not enabled

There might be issues with latest updates indeed.

My company produces signed PDFs, and for several years we embed the certificates revocation information in order to have that 'LTV enabled' mark.
Early september everything was still looking fine, but I've realized today some discrepencies.

For PDF documents generated with the same code, and the same image file (embedded into the PDF), sometimes it produces a non-LTV signature, and sometimes it does! Very weird.

But at least the behavior seems to be consistent between 2 computers, so different than what you are reporting here.

"LTV-enabled" unfortunately is not an absolute property of a signature but it depends on the local configuration of Acrobat and OS security settings.

In particular which certificates are configured as trusted by Acrobat or the OS may make a real difference:

Usually a signer certificate is not trusted directly but its issuer certificate or its issuer's issuer certificate is. In that situation verification requires access to revocation information for the signer certificate. But if you in your local configuration explicitly add the signer certificate to the trust anchors,  such revocation information are not required anymore

Being LTV-enabled means that during verification of the signature Acrobat did not need to download any external validation information. So normally for a signature to be considered "LTV-enabled" the revocation information for the signer certificate need to beì embedded in the PDF. But if that signer certificate has been added to the local trust anchors, this suddenly is not required anymore, and a signature usually not considered "LTV-enabled" may suddenly be reported as "LTV-enabled".

Similarly other verification settings may influence LTV-enabledness, too.

Thus, you should check whether the security settings on the machines in question are identical or not.