Update on my post from a couple days ago.
https://www.reddit.com/r/fitness30plus/s/UdHDBSa8aD
Took what everyone said into consideration and slowed down my next 5k way down into zone 2 only.
Took me just under 40 minutes to do 5k at almost 8:00/km pace!
My zone 4 pace is about 5:15-5:20/km...