Hi, is there a way to undo this?

Also, I definitely don't have a 6% boot rate so that's weird in of itself. I'm pretty sure I have almost never been booted, maybe once.

sigh... another case of going to multiplayer, click on quickmatch, and uncheck "invite me to multi-day games" if you want to prevent mysterious boots that are happening

Actually, your profile shows that you have been booted 12 times, maybe you don't remember them.
The boot rate takes into account your last 100 games, so just don't get booted again and you'll be fine.

OK thanks. I wonder, if you click surrender and then quit before your turn ends, does it process the surrender? Cause I swear I haven't been booted 12 times.

you were booted from 6 out of the last 100 games you played

Go here: https://www.warzone.com/MultiPlayer/PastGames
Change the Number per page to 100
Ctrl+F "You were booted"

You will find those 6 boots. If those boots are coming from games you never intended to join, go to https://bit.ly/random-invites (and optionally, send a Bug Report reminding Fizzer that the UX of signing up for QM is bad and he should fix it because this issue happens ALL THE TIME and even the engineers on the TI-84 would struggle to come up with something this asinine: https://warzone.com/ReportBug).

You can check in which games you were booted by scrolling through your past games

I remember the time in which boots were shown on profile for all games instead of just last 100 games

Pepperidge Farm Remembers

Some games require your surrender to be accepted (usually team and FFA). If it is not accepted, yoíu can still be booted.