Affected Versions:
Nightly 90.0a1
Beta 89.0b4

Tested On:
MacOS 11.2.1 / 11.0.1 /10.14

Steps to Reproduce:

1. Reach any site (i.e. : https://youtube.com, amazon.com, etc.) .
2. Start scrolling in order to achieve the overscroll effect.
3. Right click in order to open the context menu while overscrolling.

Expected Results:
The overscroll effect is done without issues and the page bounces to normal state when stopped/interrupted even if the context menu is triggered.

Actual Result:
The overscroll effect can achieve an infinite status and freeze (no bounce back) if the context menu is triggered while in overscrolling state.

Severity Suggestion:
Since this issue is present on any site and reproducible in Safari and Chrome QA suggests a Severity of S3.

Notes:
Not a regression since the feature was introduced in Firefox 89.
This is also reproducible on Safari and Chrome.

Videos:
Link1 : https://drive.google.com/file/d/1f_OzresKAEAcXW3mhLQ5_YANrJIDvPVd/view?usp=sharing
Link2 : https://drive.google.com/file/d/1CO4bdZYigwBK4SxqZepAs3PTxv7nJ0X9/view?usp=sharing

Moving to overscroll-post on the theory that if Safari has this behaviour, it's acceptable for us to have it in the initial release too.

On Windows the overscroll effect is going to be restored when the fingers lifted properly. I did confirm this issue can be seen both on Linux and Mac, but not on Windows. I guess that's because on Windows context menu is opened on releasing the mouse right button?