Gmail has lost all email labels. How can I return it?

Question

gmail

Hello. The situation is this. At work, Outlook 2007 is used in conjunction with Google Workspace (g suite used to be called). Outlook does synchronization with Gmail, calendar and so on. All folders for working with letters were created in Outlook, Gmail calls them "Shortcuts". One day there was some kind of synchronization failure and all the letters fell out stupidly from the folders into one common "All Mail". Everything that was sorted into folders is now in one folder. There, a person sorted everything for a long time and stubbornly for 5 years, about 17 thousand letters were accumulated in 300 folders. Any ideas how to put everything back in place?