Smart Video Quality setting isn't adapting to network speed on WiFi

When on slow WiFi, around 20-40% of videos take a long time to load, sometimes not at all. However, after setting the video quality settings to “Always Lowest”, all videos load at a reasonable speed.

The “Smart” video quality setting should make the video quality low automatically but it doesn’t.

App Version 1.1.15
Device: Samsung Galaxy J6 SM-J600FN, Android 10