It's because YouTube is now requiring a full JavaScript runtime in order to download and play videos. There are open issues regarding this in the relevant GitHub projects, but the fix has not yet been released.
I agree. But regarding this specific game, it seems to work through Crossover (emulation) and Parallels (virtualization). You can also try Whisky and VMware Fusion as free alternatives.
For now, I think existing exclaves such as the one that displays the camera indicator do not really apply to macOS (since MacBooks have dedicated hardware for that), but in the future there might be exclaves that do.
I believe Chrome is also the only software that enables certain mitigations such as ProcessSystemCallDisablePolicy on Windows and NO_SMT and TECS on macOS [1]. I wonder if some of these OS features have been implemented at Google's request.
However, in the case of Spectre, I think the OS should try to prevent exploitation rather than end programs, with a user-facing toggle to disable mitigations per-program for compatibility reasons.
Apple is still adding large amounts of new Objective-C code in each new macOS version [0].
I haven't found any language usage numbers for recent versions of Windows, but Microsoft is using Rust for both new development and rewriting old features [1] [2].
It also adds a new permission prompt for screenshot and screen recording apps that doesn’t allow a user to permanently grant permission, but requires a weekly re-authorization.
Not exactly what you describe, but there's Yuka for processed products (food and cosmetics). You scan a barcode and it gives you a score based on the product composition, it's quite helpful: https://yuka.io/en/
You can disable JIT in Chrome (which also enables CET [1], just like in Edge) by executing it with
--js-flags="--jitless"
You can also disable JIT in Firefox by setting javascript.options.baselinejit, javascript.options.ion and javascript.options.native_regexp to false in about:config, although you won't get CET.