MacOS and Mac computers sold right now right now is particularly ill-suited for use with OBS.
There is a thread devoted to issues relating to Catalina. I am unsure if this is one of them, as I have not updated.
macOS 10.15 Catalina Support Status
You have a 3rd party plugin installed, and I'm unsure if it has been updated for the latest OBS or the latest version of MacOS. You may wish to remove it and see if it affects your issue.
21:06:14.756: Failed to load 'en-US' text for module: 'StreamDeckPlugin.so'
21:06:16.518: Failed to open file '/Users/fabio/Desktop/okptz8osoj641-1.png': No such file or directory
21:06:16.518: gs_image_file_init_internal: Failed to load file '/Users/fabio/Desktop/okptz8osoj641-1.png'
21:06:16.518: [image_source: 'Immagine'] failed to load texture '/Users/fabio/Desktop/okptz8osoj641-1.png'
21:06:16.519: Failed to open file '/Users/fabio/Desktop/falhyksopj641.jpg': No such file or directory
21:06:16.519: gs_image_file_init_internal: Failed to load file '/Users/fabio/Desktop/falhyksopj641.jpg'
21:06:16.519: [image_source: 'Immagine 2'] failed to load texture '/Users/fabio/Desktop/falhyksopj641.jpg'
You have several image sources that are failing to load. OBS will attempt to load them every time you switch to a scene that includes them until they are either fixed or removed.
There's no output session in the log so I can't see if anything is happening during encoding that potentially contributes to the leak.