Video airplay is just inherently flawed, it seems.
I dug into some forums to try and find a solution to this, and I was able to find a few theories, none of which completely alleviated the issue for me.
Most of them centered around the wifi signal.
If you have a lot of other devices pinging Wi-Fi between your phone and the TV, this can allegedly cause disconnects and de-syncs.
If your wifi is slow, this can allegedly cause disconnects and de-syncs.
If you live in an apartment and your wifi channel is being hugged by other residents, this can allegedly cause disconnects.
I want to re-enforce the notion that none of this fixed the issue for me, but it might be worth going through the motions to see if it does for you, because some people were saying they had success after addressing these issues.
For streaming off of sites, I have actually had resounding success using my LG tv’s web browser. Connect a Bluetooth mouse and keyboard. The browser actually has a built in adblocker. You still have to deal with link redirects occasionally though.