Interesting... indeed this appears to exist in SILVA 138.1:
However, it does also exist in the GTDB taxonomy, as of R89, but not later releases:
https://gtdb.ecogenomic.org/taxon_history/?from=R80&to=R202&query=f__Fokiniaceae
In later releases of GTDB it is corrected to "Midichloriaceae".
So this is probably an issue of SILVA adopting the GTDB taxonomy but being slightly behind the latest GTDB release...