Currently I have infra with some agent backed computers. We use protection groups and jobs managed by VBR server. Jobs are forever incremental.
Week ago, new server has been added to existing protection group and after that the job ran full backup *.vbk for all servers. I dont think its usual behaviour, but maybe its just my misunderstand.
Havent tested it yet with another protection group, since there isnt much free capacity to play with

Thanks for any help/explanation
Regards Martin