After upgrading to Android 6.0, what should I do if the maximum blacklist for blocking unwanted calls is only 100?

Try Tencent Mobile Manager,

On the security protection page of Tencent Mobile Manager, select harassment interception, select Settings in the upper right corner, and add it to the blacklist. Or in the settings, select interception mode, smart mode, or only accept the whitelist, and you can customize the settings; if there are harassing calls in the middle of the night, you can turn on the housekeeper's nighttime anti-disturbance mode.