Installing ffmpeg through homebrew: dyld library not loaded

After installing ffmpeg through homebrew without any errors and after confirming that it has been linked, I get the following error when trying to run it:

dyld: Library not loaded: @rpath/libopenh264.5.dylib
  Referenced from: /opt/miniconda3/lib/libavcodec.58.54.100.dylib
  Reason: image not found
zsh: abort      ffmpeg

I've tried it through pip, conda, the ffmpeg.org website, all to no avail. Any and all help would be greatly appreciated!

I can't offer anything to help you w/ Homebrew. I gave it up some time ago due to various issues like this. I can recommend MacPorts as a package manager for macOS.

Once you have MacPorts installed, you should be able to install a functional copy of ffmpeg. I installed ffmpeg on my macOS Catalina system some time ago, and use it regularly without a hitch. Following is the port command I used:

% sudo port install ffmpeg +nonfree

nonfree was one of the "variants" available for ffmpeg; variants are explained here on the MacPorts site