Device: Samsung Galaxy Note 10 (Android 10), Google Pixel 3 XL (Android 9)
Build: Fenix Nightly/Firefox Preview Nightly 5/26

1. Open Firefox Preview Nightly
2. Go to http://jsbin.com/cacarew/4/edit?html,js
3. Tap on the Output tab from top right corner.
4. Choose to select cells by long tapping on text from one cell and drag the handle.

Expected Result: The selection can be made correctly.
Actual Result: It's pretty hard for selection to be made.

Note:

1. On Chrome the selection can be made more smoother.
2. After copying the selection when wanting to paste, the cursor remains in the last cell, could not paste after
3. The highlight for the selection is not always visible.

Video

If I remove contenteditable=true on <div> to make it not editable , the selection becomes smooth. It looks like something related to contenteditable.

Hi, issue is still reproducible with Google Pixel 3XL (Android 9) and Samsung Galaxy S9 (Android 8)

Works with Chrome.

This problem seems to occur only when selecting across multiple tables.

Simplified example:

data:text/html,<div id="ed" contenteditable="true">Two 2x2 tables:<table><tr><td>1 1</td><td>1 2</td></tr><tr><td>2 1</td><td>2 2</td></tr></table><table><tr><td>1 1</td><td>1 2</td></tr><tr><td>2 1</td><td>2 2</td></tr></table>...</div>