I don't believe this is a leak - this could be a some film or sealer of some kind.
I've seen a few Gen3 5.0L V8s have this sort of residue at this exact area, including my own - and it looks just like that, it doesn't spill over any further past the flange. In fact, if you touch it, it's somewhat tacky/stick if I recall, which leaked coolant shouldn't feel this way.
It could be, over time, heat caused whatever film to expand and spread over the area like that.
Monitor for leaks, yes, but it doesn't seem to be one. The coolant is also MC Orange or Yellow. (MY2020 Mustangs used Yellow).
Note: From info I've seen, a coolant change was made to Ford vehicles at the end of Dec 2019. Coolant yellow-Motorcraft VC13 (not green) is new and has a longer service life, replacing orange-Motorcraft VC3. (10 year/200k miles as opposed to 6 year/100k miles initial change-out)
I see. I will have to look somewhere else then since i noticed my coolant resevoir was really low. Did refill it under max line 1 month after it was on the min line
It's a press fit barb in the housing. It completely blew out on mine at a track day. The fix is pretty easy and permanent.
Remove the housing and use channel locks or whatever to pull that barb out of the housing. I can't remember what size NPT tap I used, but just size it up. You can easily tap the housing with an NPT tap.
Then go to Lowes Racing department, get a male NPT to barb fitting of the right size, and put it all back together with some teflon tape.
That is the air bypass for the coolant system. Make sure your coolant level is correct not too much or too little. Purge any air if any. Possibly replace the hose if it's dry rotted and a new clamp.
Unless like @NeverSatisfied said replace the whole barb if the leak is coming from the mating surface and not down from the hose. Also check to make sure you don't have excessive coolant pressure as that is only supposed to bypass air, not coolant, well in normal conditions, racing at a track is a bit different.