Hello,
Thank you for contacting us.
I need more details to check this issue exactly like you, please see the attachment, I have added about 100 products to the cart with no problem.
https://prnt.sc/Dh5VbDlSoWz3
Please explain to me what is your current device model and your browser and also tell me when and where you facing the issue exactly.
Please keep me posted.
Regards,