to me the real issue is this:

The average_block_size hit the limit (red horizontal line set on 25% of max_block_size = 16kB) after which the current_reserve_ratio value is decreased.

reducing current_reserve_ratio at 25% of the max_block_size

I'd like to hear the logic behind that move.

Excellent post, though, grateful to have you aboard.
[edit, I see you've had an account since 2016, but I'm just realizing you exist now :) :shrug:]