I've just had a look and I get the same I think
tim@dell-desktop:/mnt$ cd /usr/lib/x86_64-linux-gnu tim@dell-desktop:/usr/lib/x86_64-linux-gnu$ ls -la /usr/lib/x86_64-linux-gnu |grep cfitsio -rw-r--r-- 1 root root 2419662 Aug 4 2019 libcfitsio.a lrwxrwxrwx 1 root root 15 Aug 4 2019 libcfitsio.so -> libcfitsio.so.8 lrwxrwxrwx 1 root root 20 Aug 4 2019 libcfitsio.so.8 -> libcfitsio.so.8.3.47 -rw-r--r-- 1 root root 1498520 Aug 4 2019 libcfitsio.so.8.3.47 tim@dell-desktop:/usr/lib/x86_64-linux-gnu$