No, but the page parameter is incorrect and not working as I outlined above. Meaning, there is no way to fetch more than 20 members at a time in the current function.
The reason is because there is a bug in the function. You will need to adjust page%5Bcount to page%5Bsize and then the $page_size variable will work properly.
It is very easy for you to verify this. Set $page_size for example to 100 and you will see what I mean.
You really need to adjust the PHP API on github with this fix.
I just checked and yes, you can get more than 20 with the corrected code I provided you. Have you had a chance to test it yourself? And if you did, will you push this correction to the github package?
I just provided you a fix to the bug so not sure how much more I can help you. =)
Are you a third-party developer who is working for Patreon? Are you the maintainer of the github packages? If not, please let me know who I should connect with.