About a year ago I had a problem with some similarity, but not exactly your issue.
All of a sudden, my
oil pressure would drop when RPMs increased. This happened cold or hot. At idle, the pressure was within the historical range. I had put a new filter in some months before and had not too much time on it. I changed the filter and the problem went away.
What was the source? Some of the new filters (generally sold as Heavy Duty) have an anti-reversion flapper valve in the top end. This is supposed to be there to reduce
oil-drainback and keep the
oil galleries filled and ready for the next start. Well, this flapper had come "loose" somehow and was working against me. When the pressure tried to increase with increasing RPM, the flow grabbed the flapper and pushed it to close the flow stream...
The next filter I got, I made sure was just a regular filter without thid "feature".
Maybe just a filter change will help.