Your filenames located on a NAS are cut to the old 8.3-type style (DOS). They might look like this:
filena~.1. Affected files mostly contains Umlauts.
You migrated your file from a Netapp (ontap 8.2) to a Netapp (ontap 9.7).
The previous Netapp used latin1 as character set while the now used one uses utf8.
Use the Unix tool
convmvto translate the files correctly.