Since there are no replies yet I will take a stab that I hope will help get you closer and not send you off on a wild goose chase because of me being an idiot or something.
You may also know all of the following, if so sorry.
I run into Undefined symbol errors usually when some software is trying to call a function it expects to be in a library but the function isn’t because I have the wrong version of the library.
So yeah I think it may be a dependency issue.
The next thing is to figure out which package holds libharfbuzz so you can determine what version of that package you have vs what version is required by Davinci Resolve.
Something I learned about Nobara is that updating software has to either be done in the Nobara package manager or with a specific set of commands on the command line or you might break stuff (like I just did). It seems plausible that if you updated with a simple dnf update on the command line it may have caused issues.
Also… Are you installing Resolve from a Flatpak or …?