Hi @Patrick Kabole (LU) ,
There shouldn't be any performance impact on bandwidth because of multi-monitors with AVD. I haven't seen any users reporting such issues as far as I worked on AVDs. The most common issues seen with AVDs are mentioned at https://learn.microsoft.com/en-us/azure/virtual-desktop/troubleshoot-set-up-overview
Hope this helps! Please accept as answer and upvote if the above information is helpful for the benefit of the community.