Retrieve the source code linked to a specific version of your Apps Script project then save it as a new Apps Script project – RomainVialard/access-code-of-older-versions
Neat solution from Romain Vialard to retrieve a previous version of your Apps Script code. There is an open feature request to have this as a built-in feature of Apps Script (as noted by Romain recovering a previous script version is also possible using clasp using pull and an optional version number).
Source: RomainVialard/access-code-of-older-versions
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.