Question Linear depth performs different on mobile

I'm using 2019.4.19f1 and URP 7.1.8, I tried to using depth texture to fade my river and clouds when intersect with opaque objects, the opacity is determined by following code:

Code (CSharp):

1. float sceneZ = LinearEyeDepth(SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, sampler_CameraDepthTexture, positionSS.xy/positionSS.w, _ZBufferParams);
2. float depthdiff = (sceneZ - positionSS.w);
3. float alpha = depthdiff/10

while this works perfectly fine on PC, when I pack this game to Android, depthdiff will decrease quickly if I view further(even though I don't change the view direction). This phenomenon makes my water and clouds dissipate.
At first I checked REVERSE_Z issue, but I switched to GLES3.2 on my PC, and it still worked well;
And then I checked _ZBufferParams, it's the same at PC and Android.
If I push my nearclip plane further, this phenomenon will migitate but won't disappear.