The file must have been deleted (ie. marked as free space) by something but the fact Recuva reports it is over-written by an AVAST file does not necessarily mean it was the culprit.
I just had a quick check on my PC and I too have what appears to be very similar AVAST "def" files and a number of other AVAST file types also cited by Recuva as those that has over-written other files. There are at least a couple of dozen of those.
If the file is not shown by Recuva marked as green, State: Excellent and with no over-written clusters then the chances of it recovering the file in full are very unlikely.
Recuva is usually reviewed as the best file recovery software available but if it can not help in this case then it might be worth trying others now:-
https://www.techradar.com/uk/best/best-free-file-recovery-softwareI say this because like other Piriform software Recuva, Defraggler and Speccy have been inexcusably neglected by their new owners over recent years.