Certificate is not trusted

In any application that uses webview, no matter if I use the standard lineageos webview or whether I replace it with bromite systemwebview, I get these annoying popups whenever I visit most websites. This looks as follows in the application "Lightning Browser":

Some sites, such as fandom.com are worse about it than others, as this one opens dozens of popups to click through.

Here's a relevant issue in the Lightning Browser repository, though it happens with other apps as well: https://github.com/anthonycr/Lightning-Browser/issues/811

Expected Behavior

The certificate required to access common sites is available in the system, thus it shouldn't show this popup unless the site actually has a bad certificate.

Current Behavior

A ton of sites make this pop-up appear, making the web practically unbrowseable.

Possible Solution

No clue. I'm not sure what causes this error.

Steps to Reproduce

  1. Install Lightning Browser
  2. Go to fandom.com
  3. ???
  4. Profit!

Note that I could reproduce it on my oneplus2 just as well, this issue has been going on for at least a year - I just assumed it was my phone for the longest time.

/device beryllium
/version lineage-18.1
/date 2021-05-15
/kernel 4.9.268
/baseband 4.0.c2.6-00335-1227_1222_40a1464
/mods Magisk, F-Droid, MicroG

I have read the directions.

Edited by mid-kid