Hi Matteo.
Our Month View tooltips are ordered by Event Start Dates, not by Venue ID.
Do all 3 of these events in your example have the same exact start and end times?
Because I see your Month View looks considerably different from the default styling, it may be that your theme, other plugin, or custom code you’ve implemented is affecting the display.
If you think you still need additional help with this topic, please provide a link to your Month View and a link to each of these 3 events (4 links total).