When the build menu is stuck in group mode, switch your HUD back to legacy mode. This article also covers how high-impact units choose their targets and whether reclaiming ally units counts as griefing.
If your build menu shows units organized into groups and you want the simpler flat list back, open the game settings and switch the HUD back to legacy mode. The grouped build interface is useful for some players, but older players prefer the flat list. The toggle fixes it.
High damage units like artillery will aim at cheap targets such as ticks and waste ammunition on them instead of your valuable units. This behavior is especially punishing against units with high reload times. If you are defending against artillery, keep decoy structures at the front and pull valuable assets out of line of fire.
Reclaiming your teammate's units without permission can be considered griefing. The community takes this seriously enough that players get banned for repeated abuse. If a teammate reclaims a mex that belongs to another player, and the original owner reclaims it back, both accounts can receive penalties. Communicate before touching ally assets.
A build menu preference is easy to fix. A reclaimed mex is not. The real issue is always communication between teammates. Ask before you reclaim. Warn your team before you scrap something. It takes five seconds and saves the post-game argument.
[Crd] It is so easy to get on with everyone and there is zero toxicity. Just fun games of BAR which can have quite a toxic community usually.