Version: M55

What steps will reproduce the problem?
(1) Enter Reader Mode
(2) Scroll down a bit
(3) Minimize the Reader Mode overlay panel and maximize it again

What is the expected output?
The scroll position should remain the same.

What do you see instead?
It's scrolled to the top.

User feedback:
https://feedback.corp.google.com/product/282/neutron?lView=rd&lReport=18543139376