So, we were running snapshots and I can't remember when it started but I believe it began in 20w17a during the 2x2 tree bug. I didn't think too much on it because it was supposedly fixed in a later version and we stopped updating due to certain bugs but now that were are on 1.16.1 I've noticed a persistent problem in all of my worlds that were loaded in the snapshot. Even after optimization, 2x2 jungle trees absolutely will not grow when next to other 2x2 jungle trees, fully grown or just saplings.