I think there are several causes of the nade spam. First off its their range. This games movement is most similar to H2/H:Reach. In both of these games grenades couldnt be thrown as far, didnt bounce as much and had smaller blast radius. So they were mostly used as utility right before a fight or during a fight to weaken your opponent. In Infinite it seems like they just copied grenade physics from H5 which had much faster movement speed, dash ability available at all times and bigger maps. It just feels wrong in this game. Because of their range and bouncyness they simply cant be used effectively at close range anymore, otherwise youd have to aim at your feet which isnt ideal, especially on controller. Now theyre used to scout out rooms and kill people across big distances who are behind cover

Secondly, hit markers. They were turned off in competitive for a good reason, and 343 should disable them for social/casual as well. They simply give you way too much information. You can throw a grenade into a small corridor or a room and know if your opponent is weak enough to be an easy kill. On a receiving end theres nothing you can do about that and it feels very frustrating.

Thirdly, no friendly fire. Not having to worry about accidental betrayals definitely makes grenades a no-brain tactic in a firefight. Just chuck a bunch of grenades and hope for the best.

Fourth-ly?, ive noticed that 4v4 maps seem to be a lot more claustrophobic than in previous games. Just look at Streets and Recharge. A lot of tiny rooms and tight corridors everywhere.When a simple grenades blast radius covers an entire room youre in it definitely contributes to the feeling that grenades are a lot more oppressive than in other Halos.