Please accept my sincere apologies for the delay and for requesting the same information twice, I should have noticed it.
Regarding this issue, we've just reviewed the information of the Bitnami support tool and found that WildFly was killed during its execution. You can check the content of the /opt/bitnami/wildfly/standalone/log/wildfly.out and you will see this error message
*** JBossAS process (30147) received KILL signal ***
The machine may ran out of memory and that can be the reason why the service was killed, can you monitor the instance using the Google Console and the following commands inside the machine?
ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS
ps -e -o pcpu,nice,state,cputime,args --sort -pcpu | head -10
You can also try resizing the server and checking if the server is more stable after that.