create trigger tr_bc_view
before create view
Now, see the trigger's type:
select rdb$trigger_type from rdb$triggers where rdb$trigger_name = 'TR_BC_VIEW'
You get 540672 (HEX 84000).
Backup the database.
Restore the database.
Now, query the trigger type again (same select as above), you get 16384 (HEX 4000).
So, the bit 19, which says that this is "create view" trigger is lost during backup-restore and this trigger is unusable.
This happens with triggers defined to fire on views, as well as with triggers defined for exceptions, roles, indexes and domains. The triggers which fire on other objects do survive (triggers on tables, procedures, etc.).