Reading some comments on this complaint, most people seems using ATOK as a
Japanese IME.  So ATOK is doing something special about sending backspace.

For some Android models sold in Japan, ATOK is pre-installed and quite a few
users may be experiencing this.  Raising priority.

Changwan@, could you try installing ATOK to get a repro?
There's a free trial version.
https://play.google.com/store/apps/details?id=com.justsystems.atokmobile.tv.service

I found a comment that an ATOK user on GalaxyS7 edge
didn't experience this, so there may be some workaround even when
ATOK is used.
https://play.google.com/store/apps/details?id=com.google.android.webview&reviewId=Z3A6QU9xcFRPR2JVWnVld1dRXy1PZms4ZjI1TWlucldjWmRremxMaUJEQm85NEtLb3RIM2xOQzFmbFNHSnNzd3V2bERMOVl5dl8wSWZxSktrWjJvbXZlWkE

This issue seems to have happened since M54 (late October).

Hypothetical repro steps:

1. Install ATOK
2. Open a web page that contains text field with WebView
3. Type something (without commit)
4. Hit backspace (green button with "X" label)

re comment#3, ATOK backspace button in on-screen keyboard was not green,but dark gray. (may differ via some setting)

I cannot reproduce this with ATOK on Nexus5X (running 7.1.1) + Twitter app.

I couldn't reproduce this issue on ATOK trial version + Nexus 5X (N) + Inbox app + WebView 54.0.2840.98 nor on current version 55.0.2883.91.

In any case, it is difficult to imagine how backspace can be converted into clipboard paste because they go through completely different code paths. It is possible that ATOK is using clipboard paste as a workaround for some issue, and the timing change might have affected it.

To summarize the findings from kochi@, conops and TAM so far:

This occurs only on SUPER ATOK ULTIAS, which is a pre-installed version of ATOK , mostly found on Fujitsu phones (F-02H).

And it seems that the issue has been fixed on recent models (such as F-01J), and this issue doesn't repro on public versions, which means that this is likely not WebView / Chrome issue.

I also tried to reach out to JustSystems, the developer of ATOK keyboards, but there was no response so far.

Looks like the OTA update from Fujitsu for this issue has started for some models.

Once we confirm all models that we are aware that is affected get updates,
we'll close this.

Looks like all affected models got (or will get) OTA updates.

e.g. for F-04G
https://www.nttdocomo.co.jp/support/utilization/product_update/list/f04g/index.html
> 改善される事象
> 文字入力時、まれに正常に動作しない場合がある事象です。