/usr/lib/swift/bin/lldb: symbol lookup error: /usr/lib/swift/bin/../lib/liblldb.so.13git: undefined symbol: _Py_Finalizing
Would you be able to specify what Linux distribution you're using and its exact version? We'd also need to know the exact version of Swift you're using, how it was installed, how exactly REPL was launched, and what commands within the REPL trigger this error. Thanks!
Unfortunately Arch Linux isn't officially supported right now. I recommend reporting this issue to whoever creates Swift packages for this distribution.