Drain level does not match stable

Describe the bug:

When a map have hp drain 6, just some 100 and 50 can drain a lot of hp. After that, just one miss and you lost. In osu stable it’s not hard at this point.

Screenshots or videos showing encountered issue:

https://youtu.be/vaOy9Dgqt2A

osu!lazer version:

2020.221.0

Logs: please attach logs here, which are located at:

• %AppData%/osu/logs (on Windows),
• ~/.local/share/osu/logs (on Linux & macOS).

I’m on android

[aemino]

I hope this anecdotal case is all right to post here, apologies if not. I was playing this map on master and maintaining ~91-92% accuracy for the first minute, but my HP slowly dropped, leading to it bouncing around 20% by 1 minute in. This meant that when I hit two "meh"s within a small timespan I instantly failed the map with 92% accuracy.

I notice similar behavior with other maps too; some maps (due to the spacing of notes or BPM?) tend to have cases where your HP can drop to a very low percentage and then not recover while maintaining a “local” accuracy of >90%. Is this desired behavior?

[bdach]

Generalising this as drain has now been called both too harsh and too lenient, so clearly the user expectation is that drain will be exactly the same as stable (which, to emphasise, it might not necessarily end up being).