I encountered a strange phenomenon when displaying Khmer in web browsers.
I am not sure where to report the problem as I am not sure if it is the font, the browser or the operating system that is causing this problem.
Have you guys experienced this kind of problem before? What do you think is the cause?
Cases where the problem occurs
Windows 10, Chromebook (does not occur on iOS)
The same problem occurs in Chrome, Edge, and Firefox.
I confirmed the problem when I used Noto{Sans,Serif}Khmer and DaunPenh.
No problem when using Khmer UI
Problem Details
Diacritics are incorrectly positioned when certain strings are repeated four times.
When repeated more than 5 times, the position of the diacritic shifts.
The image uses 'ខ្លាំ'.
It can be reproduced with another string as long as it is a combination of a consonant, a subscripted consonant, and a vowel on the right side.

Comments
It was a bug in Harfbuzz. Thanks for the great information.
I'll be waiting for the retail version of Chrome to fix the issue.
https://github.com/typotheque/text-shaping/blob/main/docs/otl.md
Is it correct to understand that "Chrome" doesn't necessarily use Harfbuzz?
I often get confused by the relationship between the browser, the rendering engine, and the shaping engine.
But it's exciting to see many engineers working together to solve the problem.
Thank you for your kind information.