Sometimes save icon is not color filled (but article is saved correctly) on app (6.8.1 and earlier) on iOS 14.6 and earlier.

Screenshot shows successful saving as indicated by the reading list suggestion, but icon color is not filled.

Update: I discovered a possible cause and with it another symptom:

Say (on the app) by reading Dew point , you click on the wiki link to https://en.wikipedia.org/wiki/Relative_humidity, it redirects to https://en.wikipedia.org/wiki/Humidity#Relative_humidity.

Because of the #Relative_humidity, the save icon is not filled, and the other symptom is that the table of contents in the app shows the article title as "Relative humidity" and not the correct "Humidity".

I hope that helps.