Timezone issue (user setting not applied when creating an event)

Demoed in 5.0.0 by Mathilde (Kalepin). To be reproduced in latest version

https://v2.lekalepin.fr/events/f39eeceb-e2ea-49be-93dc-fe223c313adb

Although user has "Paris" in his default settings, when she creates a new event, the event is created without timezone. As a result it is wrongly displayed.

If going on the event and forcing the timezone to Paris, the event time is shown correctly.