When the episode aired, some people said it was ridiculous for Rukia to fight alongside Ichigo, ignoring the fact that Renji later fought alongside Ichigo as well. Fighting alongside Ichigo didn't make either character scale to his level, since neither of them demonstrated anything that would justify scaling them anywhere near Ichigo's level, unlike Orihime in the last episode, who actually demonstrated something that affected the scaling.

To begin with, one of the things people claim is wrong is that Rukia freezes Yhwach's power. However, this doesn't cause him any problems. In fact, Rukia freezes him, and Yhwach simply takes it in stride.

In the next scene, they both prepare to attack the god together, but Ichigo arrives first. He exchanges blows with Yhwach while Rukia is barely making her way over to launch her attack. Yhwach pushes Ichigo away, and Rukia stops because even she knows it would be ridiculous for her to attack him. Yhwach himself tells Ichigo that fighting alongside Rukia is holding him back.

In the next sequence, they attack Yhwach together, and he unleashes a black energy beam. Ichigo leaps into the air and fires a Getsuga Tensho combined with a Gran Rey Cero from above, while Rukia attacks from below. Ichigo lands his attack, while Rukia only manages to strike Yhwach with her ice, which once again seems to be of no concern to the god. She only reaches Yhwach with her sword afterward, just for him to pierce both of them with another black energy beam.

This is where the fight ends, because Ichigo then activates his Bankai, and Rukia only releases hers afterward, only to be pierced by Yhwach's sword. At no point during the fight did Rukia fight alongside Ichigo at his pace, nor was she of much help.

Fighting alongside Ichigo is not enough to scale Rukia to him. Nothing in this fight suggests that Rukia is operating on Ichigo's level, and the fight itself actually shows the opposite.

I hope this post helps clarify that.

About Rukia in battle against Yhwach