Comment 3 for bug 1766046

===As requested ===
$ dpkg -S libzstd.so.1
libzstd1:amd64: /usr/lib/x86_64-linux-gnu/libzstd.so.1.3.3
libzstd1:amd64: /usr/lib/x86_64-linux-gnu/libzstd.so.1

$ ls -l /usr/lib/x86_64-linux-gnu/libzstd.so*
ls: cannot access '/usr/lib/x86_64-linux-gnu/libzstd.so*': No such file or directory

===Plus some more things that might be of interest===

Yet the package claims to be installed
$ dpkg -l |grep libzstd
ii libzstd1:amd64 1.3.3+dfsg-2ubuntu1 amd64 fast lossless compression algorithm

Try to purge it
$ sudo apt-get purge libzstd1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 dictionaries-common : Depends: debconf (>= 1.5.5) but it is not going to be installed or
                                debconf-2.0
                       Depends: libtext-iconv-perl but it is not going to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

Same failure after creating empty libzstd.so files with touch (them removed them).

Nor is the libzstd1 package in the /var/cache/apt/archives directory.

Tried to download the libzstd1 package:
$ sudo apt-get download libzstd1
Get:1 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 libzstd1 amd64 1.3.3+dfsg-2ubuntu1 [189 kB]
Fetched 189 kB in 1s (335 kB/s)
W: Download is performed unsandboxed as root as file '/usr/lib/x86_64-linux-gnu/libzstd1_1.3.3+dfsg-2ubuntu1_amd64.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)

Nothing showed up in /var/cache/apt/archives.