Suggested workout: Interval training (Treadmill) - useless datafield screen

Today I did 3 firsts:

first Treadmill run

first Suggested Workout according to what the watch suggests

first Interval workout

(usually I run "freestyle" outdoors)

and I'll add, because maybe this is also relevant, that I have a fenix 6, FW: 25.10

Because of the so many firsts I am not sure if I am doing something wrong, or I am right to say that the suggested workout UI is crap, unusable, in fact it probably makes things worse, and was better if it didn't exist?

So today the Suggested workout was: 15:00 @ 6:25 warmup , 6 * (1:00 @ 4:25 pace and 3:00 @ 7:25 recovery), 10:00 @ 6:35 cooldown . 

My problem is that at every stage (let's call it lap) the gauge shows some average, it's not clear of what, IMHO it's not the average of the current lap. Maybe it's the last X minutes' average, maybe it's the current and the previous lap's average (which makes no sense to display)? So the problem is this:

Let's say I am running the 1st interval, I see on the treadmill setting and even on the fenix6 when I go down 1 screen, that my actual pace is 4:25, or even faster (I was even faster than 4:00 at the 1st interval, because I was looking at the gauge, and it told me I'm too slow).

Then I finish my 1st interval and start the 1st recovery. I slow down the treadmill and I see on the watch that my pace is around 7:25, but the watch constantly tells me for at least 2 minutes that I am too fast. So again, because I am looking at the stupid gauge slow down even to slower than 8:00 pace.

And this goes on...

What am I doing wrong? I feel like I am doing the suggested workout but the gauge... it just misleads me, totally useless.

I have a feeling that this is a bug in the watch, but because I never used the watch on treadmill before, nor did I suggested workout interval training, I'm not sure. Maybe this worked in a previous FW? Maybe it never worked? And is it intended to work this way (I hope not, 'cause it's very confusing)