Started with OH3 M1 a while ago and moved on to M4 meanwhile. As soon as I create homematic IP based things and items (no rule active so far), the Disk IO is going wild start writing megabytes
The question is what component of OH is doing this I/O? In the Homematic binding there have only been some little changes for a better compatibility. I don’t think that the binding itself produces does more reads.
I’d ignore that for the time being as there’s substantial issues with thread/rule scheduling in M4. Possibly fixing those will affect your issue as well.