thx.

How do I proceed to the log?

$ flatpak run --command=sh --devel org.gnome.Calendar
[📦 org.gnome.Calendar ~]$ gdb /app/bin/gnome-calendar
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Reading symbols from /app/bin/gnome-calendar...

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(No debugging symbols found in /app/bin/gnome-calendar)                                                                              
(gdb)