A couple of months ago I blogged about how you can stop Safari from switching your Twitter timeline by selecting "Disable Removal of Non-Cookie Data After 7 Days of No User Interaction (ITP)" in the "Experimental Features" submenu of Safari's "Develop" menu. If you don't select this experimental feature, then Safari's "Intelligent" Tracking Prevention will automatically, silently remove some crucial Twitter user data if you don't visit twitter.com for a week. I've now discovered, however, that my workaround is only temporary. It turns out that Safari automatically resets your Experimental Features preferences after a software update. I've confirmed this on two different Macs by looking at defaults read com.apple.Safari before and after first launch of the Safari 15.6.1 update. I've also seen the Experimental Features preferences get reset on iOS. I suspect that the Experimental Features preferences get reset on every Safari update now, because I found a reference to this behavior mentioned by an Apple engineer for a previous Safari update.
Honestly, I'm at the point where I'm going to disable Intelligent Tracking Protection entirely ("Prevent cross-site tracking" in Safari's non-experimental Preferences). It's crap like this that makes people switch from Safari to another browser. Things are broken in Safari that work fine in other browsers. It makes me sad, because my browser extension StopTheMadness works best in Safari. I don't want people to switch away. I criticize Safari's shortcomings because I want Safari to be better. I need Safari to be better.