I've so far seen this on the 9.14 beta and on 9.17.
When I'm in a Running activity, the watch display is on almost the entire time. I've confirmed that it was set to SHORT timeout and LOW sensitivity. Auto brightness and constant 20% brightness does not change anything.
I think it has to do with my run cadence or arm carriage. On an easy run (7:30-8:00/mile pace, around/just under 170spm), the display stays on. There is no delay when raising my wrist to look at the watch. It is sometimes dim, and brightens up in the sunlight (even with autobrightness off, see https://forums.garmin.com/sports-fitness/healthandwellness/f/venu-2-plus-964331130/293945/manual-brightness-is-weird-when-in-direct-sunlight-the-watch-decide-itself-to-level-up-is-it-a-feature-or-a-bug-v8-12-and-v9-17)
When running faster (under 6:30/mile pace), the display turns off quickly, which I verify by raising my wrist to look at the watch within ~10sec of lowering it (the display is blank, not dim, and turns on with a slight delay). At higher speeds my cadence is faster (above 173spm).
I also saw good results when using a higher cadence at easy run paces, but it's not natural yet to run at that cadence on easy runs.
Does anyone else have this issue? I've seen it use up to 2x the battery life on a run, compared to similar runs with Gestures turned off.