Yes I am pretty surprised that I lost most of the Tags I used when the Threads were migrated to Folders.
It is important that you warn the user with a message like "Please note that if you have at least one Thread which uses more than one Tag, we will select one of your Tags at random as the Folder name and you will lose all other Tags"
I used multiple Tags for many Threads : e.g. "Work" + "Python" + "Training Material". After the upgrade, such a Thread is moved to ONE folder, but so far, I have not found the logic used to select the folder.
Suggestion to the Devs: Maybe offer to create folders that uses ALL the Tags; so in the example above the folder could be "Python - Training Material - Work", while another Thread could be moved to "Python - Work" if it was using those 2 tags only