Exchange 2016 install size bloating

We manage several Exchange 2016 machines with all mailboxes online. So Exchange is only used for recipient management and smtp relay. We keep them updated with latest cumulative updates. We notice that install folder is using more and more space. That is not log files using space, we clean logs regularly. Especially "...\ClientAccess\Owa\prem folder seems to be taking up most space. Is this normal, any way to reduce the size? Seems like with each new CU install we have to expand the partition by 2-10GB. Here's a sample screenshot showing space usage