New screen during activity

I found this in 21.00 release notes:

Added enhanced strength functionality, which includes an improved workout preview with a map of muscles that will be used, improved UI in free mode and workouts, and improvements to the rep and weight editing experience.

But I don't understand what it means.

Is it the Running Power plugin that you installed? I have no personal experience with it yet, so cannot help much, but there is some description available at https://discover.garmin.com/en-US/performance-data/running/#running-power, and some more details may be perhaps explained in the FAQ at https://support.garmin.com/en-US/?faq=fwWveMrazC8ODmim11oeM7 

BTW, if this is your activity, then I see you are using the Running Power add-on without a HRM or footpod. It won't work without it. The values on the display have probably something to do with the wind, that is being taken in account by the Running Power plugin, but as long as you do not have the Running Dynamics data from a HRM or a footpod, it is useless. If you do not plan purchasing the HRM or footpod, you can uninstall the RP plugin - it won't give you any useful data.

Thank Trux, yes the activity is https://connect.garmin.com/modern/activity/8819341774 

I haven't HRM cause I'm waiting for a new one from Garmin for a failure

I wrote an email to Running Power dev but I'm seeing in the app page that its latest updated it's: 18 January 2022 (I've never seen this screen before...).

Thanks

It's surely something related to segments.

This morning (in the proximity of a segment) it notified to me that I wa x meters near the start of the segments with a meter countdown. Then the screen I posted appeared and a result screen after the segment completion.

It is related to a segment. Shows your time ahead/behind 

Segment tracking isn’t new. Been around for a while.