Came across this today and had a horrible time trying to see anything. Whilst waiting for SE's fix, here's a script that fixes this for me.
IDK why the code works, but the problem is that the table's width: 100% isn't propagating down to the tds.
// ==UserScript==
// @name Code Review Fix Overflowing Tables
// @namespace Violentmonkey Scripts
// @match https://codereview.stackexchange.com/posts/*/revisions
// @grant GM_addStyle
// @description https://codereview.meta.stackexchange.com/q/10589
// ==/UserScript==
GM_addStyle(`
#revisions > table > tbody > tr > td {
max-width: 1px;
}
`);