Good thing you brought this up. I couldn't believe that your recording where ADPCM because in our 3CX we just have PCM recordings.
It turns out that the ADPCM codec for recordings is a completely new feature in 3CX, which arrived in the latest version 15.5
I had to dig around before I could find that setting anywhere. But it's under the recording quota.
IMHO you should have a lot of recordings to enable it in the first place. In just 10GB you have room for 167 hours of non-compressed recordings. But maybe some users have it set up to recording everything on every call and a lot of extensions and small cloud hosted VMs.
3cx_compress_recordings.png
