Shooting street at night with the a6700 is Auto ISO actually usable or am

Been taking the a6700 out after dark more lately. City blocks, storefronts, people moving through lit intersections. The kind of shot where the light is doing exactly what you want for about four seconds and then it's gone.

My issue is Auto ISO in manual mode. I have it set with a ceiling of 12800 and a minimum shutter of 1/200 to freeze movement, but the camera keeps making choices that confuse me. Sometimes it pushes ISO way up when the subject is clearly standing in a pool of streetlight and I feel like it should know better. Other times it underexposes and I have no idea what logic it followed.

I shoot with the Sigma 30mm f1.4 wide open basically the whole time. Wondering if the metering mode is doing something I haven't thought about. Currently on spot, but maybe that's working against me more than helping when the frame is half shadow and half neon.

Do people here actually trust the Auto ISO behavior for this kind of shooting, or do you go full manual and just chimp constantly? Also curious whether anyone swaps metering modes depending on the scene or just picks one and leaves it.

Not looking to shoot at f8 with a tripod. This is fast, handheld, whatever the street gives you.