How to reproduce:
1. Open the "SampleScene" Scene in the attached "case_1214921.zip" Unity project
2. Build and run on an Android or iOS device
3. Press the "Render Inteval" button to change the OnDemandRendering.renderFrameInterval() value between 1 and 3
4. Observe the red image on the screen

Expected result: the Image's opacity does not change or no additional semi-transparent images are rendered
Actual result: the image's opacity changes or additional images are rendered on top of each other

Reproducible with: URP 7.1.1, 7.1.7, 7.1.8, 7.2.0 (Unity 2019.3.1f1, 2020.1.0a23)
Not reproducible with: URP 7.0.0
Could not test with: 2019.2, 2018.4, 2017.4 due to URP not being available; URP 7.0.1 due to builds being unsuccessful

Reproduced with:
VLNQA00296 iPhone 11 iOS 13.0
VLNQA00244 iPhone 7 Plus, IOS 12.0
VLNQA00288, Samsung Galaxy J7 (SM-J730F), Android 8.1.0, CPU: Exynos 7 Octa 7870, GPU: Mali-T830

Notes:
1. Not reproducible in Play Mode in the Editor
2. The behavior is reproducible when OnDemandRendering.renderFrameInterval() is set to a value bigger than 1
3. On version 2019.3.0a10 (URP 7.0.0) the issue is not reproducible in Play Mode, because the image's opacity increases upon entering Play Mode; the image gets more opaque in the Scene view when the Editor is unfocused and refocused continuously.