I have a really weird problem. When playing videos in Safari—especially Facebook Reels—it lags every 10–20 seconds. In Chrome, everything works perfectly.
Even stranger: if I try to record the issue using the built-in screen recorder, the lag disappears… 
This has been going on for the past five years or so, and I’m getting extremely tired of it.
I’m currently using an M4 MacBook Pro with 500 Mbit fiber (previously an M1 MBP, and before that a maxed-out Intel 15” MBP), so it’s definitely not a hardware issue.
The worst part is that it’s really hard to troubleshoot since the problem is intermittent. For example, if I reboot, the lag won’t come back right away—it might take minutes, hours, or even days, to return.
I also turned off the Private Relay service a couple of years ago, but that didn’t help.
I recorded a session with my iPhone, you can see the lagging att approximately second 10, 20 and 45: iCloud Drive - Apple iCloud
Any ideas before I lose my mind? 