App Version: 70.0.3501.0 Canary
iOS Version: 10.3.3, 11.4.1, 12.0
Device: iPhone 6

Steps to reproduce:
1. Launch chrome 
2. Tap on the tab Switcher
3. Tap on plus to add New tab

Observed results:
Grey screen is shown for a moment on Open New Tab

Expected results:
Grey screen should not show when Open New Tab

Number of times you were able to reproduce: 5/5
Bug reproducible after clean install: Yes/No
Bug reproducible after clearing cache and cookies: Yes/No
Bug reproducible on Chrome Mobile on Android: Not tested
Bug reproducible on Safari/Firefox: Firefox: NA, Safari: NA
Bug reproducible on current stable build (App Version, iOS Version): No M68 
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes on M69 

Link to video:
https://drive.google.com/file/d/1KX6TLzG4CA-CWhPL5pfBRa9p94mRvdDU/view