I get the feeling but this is an entirely different situation here for Various Reaons;
1.) Wanda is honestly at her most weakest we have ever seen her in the MCU, after the expanding the Hex in episode 6 she is clearly weaker, more tired and is under allot more stress and uncertain about nearly Everything in her life right now. She has in her mind lost her husband's trust, her Brother is not her Brother and she can't understand where he came from and now her Children are missing. She is approachind a Rock Bottom state and when anyone is like that no matter how strong you have been before, you can't hope to muster the power cause of all these factors.
2.) Wanda while she was indeed greiving in Endgame she was completely in Rage and Vengence mode, to Avenge her murdered husband. She went Super Saiyan in this Regards and let her Angry fully full her Attack, her anger made her clearminded with one goal on killing Thanos with not uncertainy in her mind, clearly a 180 where she is by the end of episode 7.
3.) Thanos with how powerful he truly is and dangerous, he is just a Power Fighter based in Physical Attacks and Strenght mostly. Wanda's powers driven by her rage clearly where his achilles heel to that which when she gain the advantage left him totally at her power.
4.) Agatha is more of a MindGames fighter with powers that are showing Mental Control and Manipulation over Wanda, so it is a fight against not only someone simliar to herself, but is very much well more trained and expriened in using such powers. Ontop of that she Wanda has been broken down bit by bit to her weakest state and when you have such a power user that can effect you mind and magic, you really might as well have no phycial control over anything.
5.) Finally and Most Important, this is AGATHA! We Don't Want Wanda to Waste her, we Want that Teacher and Student Relationship from the Comics!