IMO if you are stopped, that’s part of the average 😉 . I know it’s a frustration with road rides in that you want to assume the ride was all non-stop but have to stop due to lights.
However, I find Strava is usually a bigger average figure than Garmin if I just leave the thing un-paused. Strava accounts for stops in the data and they prefer you don’t auto-pause. Also I was finding auto-pause was screwing things up making a slow steep climb (this is off-road) seem to take a couple of seconds and I kept getting KOMs and rides would get flagged. That was pre-Garmin on an old phone though years ago.
Not that I really care. I go with how many miles did I cover in the time I was out, and even then I’m not bothered if I’ve crawled along so long as it was fun. I also don’t do leaderboards etc any more.