cellphone app very slow / irresponsive

One of our users is experiencing the following problem:

"The Zoom mobile app is extremely unresponsive, especially when I try to end phone calls by pressing the red button. I have to press it 4-5 times, which often results in calling a random person once the call screen finally closes. The unwanted call, then again, is difficult to abort. In addition, I am sporadically unable to answer phone calls due to a charging icon appearing and a message asking me to "please wait" after pressing the blue button to take the call.

I am running the current version 5.14.6.13477 and my phone is a Galaxy S20 Ultra 5G, Android 13, One UI-Version 5.1, Modelname SM-G988B/DS

As I use Zoom phone for work, it would be important to improve the situation. Any ideas would be appreciated. Thank you!"