Android can be a headache at times.
It seems to struggle with 'always on top' apps especially when it comes to sound.
If you use an app like tunein radio, Google music or a custom MP3 player app and then go on Facebook/IG with them playing, every time you scroll past an autoplay video the music is stopped in lieu of the video on screen (or you might hear both play if you're lucky).
It's beyond annoying and been happening on android forever. Different apps seem to have different priorities as to what is played and even muted, videos can cause sound interruptions - which is bonkers.
Turning every autoplay option off isn't even a guarantee of it stopping!
You can disable the overlay settings in the developer options to stop tiny little video screens from popping up, but that reduces features from apps like FB & Twitter that are utilising this feature themselves now.
(There may be a Chrome option to help - see * below).
Rooting the phone and adding Ad blockers would help, but is a huge chore to do and maintain (plus videos support the site!).
So it's kind of part and parcel of the OS and hopefully Android Q may address this.
If you experience any slowdown on loading this site via chrome, this is part of the same kind of issue. As the page tries to parse Twitter, Facebook & YouTube urls (which is a relatively new feature), the browser really struggles - then throw in an overlay video ad and it may take a bit longer than you'd like to all appear correctly.
*Possible Chrome option fix:
(possible as not all OS/versions of Chrome have this setting anymore, but worth a look).
1. Open Chrome browser app.
2. Tap options (3 dots in top right corner).
3. Tap settings.
4. You will see a basic & advanced section. Tap 'site settings' in the advanced section.
5. Tap 'media'
6. Toggle 'autoplay' to off.
That may help assuming you can see the option in the first place.
The screen overlay option is the next step if you really want to knock sound issues on the head when surfing. As David said, keep in mind it may be a rogue video, but what you describe happens daily to myself in many other scenarios.
Regards,
FWD.