@julian 3.2.0. You're right, it is crashing; I found the following the error log:
error: uncaughtException: Cannot read properties of undefined (reading 'upload')
Jul 08 19:13:55 ich-bb env[1008]: TypeError: Cannot read properties of undefined (reading 'upload')
Jul 08 19:13:55 ich-bb env[1008]: at Controllers.handleUpload (/home/nodebb/nodebb/node_modules/@nodebb/nodebb-plugin-import-users-csv/lib/controllers.js:22:17)

Also, I'm running node 18.16.1, connect-multiparty 2.2.0, and the version of multiparty installed in node_modules is 4.2.3.