While she was once the most powerful agent in the game, Sage has seen nerf after nerf since release. Now, she's more of a niche pick than a must-have on every map.
For instance, pro players often play sage on maps like Split, Icebox, and Bind to cut off specific angles and prevent opponents from wall-banging them. She's still a part of the meta, but some teams opt to run a Viper or initiator instead of Sage. She only seems to get weaker as other agents get stronger.
In the 3.06 patch, Riot made a change to the Icebox map that will, in my estimation, make a direct impact on Sage's pick rate on the map. The change is in the B-side default plant spot, preventing it from being wall-banged.
The meta of using Sage to deny mid tube has fallen a bit out of favor in the pro scene, as players find more creative ways to utilize the middle of the map. Still, Sage is routinely used as a way to block the wall-bang spot on B default, which is no longer a problem.
After all, blocking this angle doesn't do too much to prevent defenders from pushing, since they can still come from two to three other angles when they retake the site. Now, a Viper, Astra, or another Sentinel with more utility can hold the angle just as well - if not better - than Sage can.
Wall-bang changes were not isolated to Icebox, but the default plant at B almost always required a Sage up until now. I'll be interested to see how pro players utilize the new map feature, and if they decide to step away from one of Valorant's oldest meta picks.