FPC restart after max-queues-per-interface configuration 

FPC will get restarted after applying the max-queues-per-interface at chassis

set chassis fpc X pic y max-queues-per-interface (x)

Please refer below document for more details

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/max-queues-per-interface-edit-chassis.html