I went back to Chromium for now.
Vivaldi was eating a lot more CPU, and I got a lot more zombie processes I had to kill.
Plus Chromium didn't make good on its threat to kick out Google sync logins.
I'll try Vivaldi again, though.

外国人でさえ諦めてvivaldiに戻ろうとしている
ちなみに回避方法は一切存在しません（調べてみたらわかるけど）あなた達も彼らみたいに諦めることになるのだ