Watchface pulsating/flickering between low and high brightness every 1 second when in low power mode

My watchface has an issue where - when AOD is enabled and the watch enters low-power mode -
then after a while the watch begins to pulsate/flicker between high-brightness and low-brightness every 1 second;
I.e. it remains in low-power mode (I can tell that b/c my low-power vs high-power WF look very different),
but instead of refreshing/onUpdate every 1 minute, the watch goes high-brightness, then 1 second later to low-brightness, then repeats high-brightness and so on.

Sequence:
1. watch starts in high-power, displaying my high-power-WF
2. after the few/8 or so seconds watch enters low-power mode and displays my low-power-WF without pulsating
3. after a while it begins to pulsate while still showing my low-power WF:
3.1. it shows my low-power-WF using high-brightness
3.2. after 1 seconds it shows my low-power-WF using low-brightness
3.3. repeat/goto 3.1. above
if I then tap/gesture, it goes to 1. above and the flow repeats itself

Any idea what I might have missed/been doing wrong ?
Otherwise - might be related to forums.garmin.com/.../watch-face-updates-coming-every-second-while-in-low-power-mode-on-9-33

Notes:

1. this happens on an actual device (Epix 2 PRO 51mm) and I cannot reproduce it in the sim

2. likely irrelevant but just in case: as per sim my low-power WF luminance usage of about 1% as per 24hrs burn-in test

3. I have not impl/use onHide and onShow in the WF

4. as far as I can tell the trigger for the flickering/pulsating is not related to an external event, or at the least not 100% of the time: 
4.1. watch starts in high-power, displaying my high-power-WF
4.2. after the few/8 or so seconds watch enters low-power mode and displays my low-power-WF without pulsating
4.3. while in low-power and not pulsating I sent a text message from another phone to my phone
4.4. notification showed up on the watch
4.5. after few sec notification disappeared and watch returned to my low-power WF and did not pulsate
4.6. few minutes later still the same, i.e. watch displayed low-power WF and did not pulsate