During the pandemic, the Paris Airports authority closed Terminal 1 (which you use for Lufthansa and United, among other airlines), and then kept it closed for refurbishment.
It started reopening progressively as of today.
Réouverture du terminal 1 de l'aéroport Paris-Charles de Gaulle : ce qui change pour les voyageurs
https://www.lefigaro.fr/voyages/reouverture-du-terminal-1-de-l-aeroport-paris-charles-de-gaulle-ce-qui-change-pour-les-voyageurs-20221201?utm_source=app&utm_medium=sms&utm_campaign=fr.playsoft.lefigarov3
Here is a link in English to the airport website that says which airline will move as of what date: United won't move back to Terminal 1 until Jan 9, 2023, while Lufthansa moved back yesterday.
https://www.parisaeroport.fr/en/passengers/flights/airlines-company-transfers-pariscdg