It's nothing new, it's a removal.

To all the people commenting about lockstar, customization of AOD is completely removed in 6.1 update

Same problem, actually it's 5g which is doing it, in my case. Please use 5g wisely, or if you need continuous connectivity, maybe using 4g will be better option. I have created a routine to do switch it manually, you can automate it, as per your need...