> The orange microphone dot indicator and its very colored friends can no longer have their brightness changed for dimming them, which made my YellowDot app useless [1] (I guess this is for privacy

It absolutely is for privacy, to stop malware or trojan programs from obscuring their accessing the camera or microphone.

> Reference Presets no longer allow setting arbitrary SDR nits, making it impossible to natively unlock 1600nits of brightness on MacBook Pros or 2000nits on Studio Display XDR which breaks my Lunar app [0] (this seems to be intended, no idea what hurt Apple that they had to block this under SIP)

OLED displays are widely expected this year. Not wanting to have to deal with "my battery life is an hour and a half instead of 10, what's going on!? Replace my battery!" nonsense is probably the remainder.