uBlock Origin. The easy customizability of web applications is why I prefer them over other proprietary applications when there are no open source choices.

In this particular case, if the whole UI is irredeemable, you can access your mail with IMAP or POP.

> uBlock Origin.

I did try this without success.

> if the whole UI is irredeemable, you can access your mail with IMAP or POP.

I access my mail across a doz machines - and I support scores of users. Setting up stand-alone/3rd party clients (at scale) is a bit unwieldy.

The bad actor here turns out to be the Chrome browser. Every other browser behaves better in this.

  mail.google.com##div[aria-label="Message Body"] span[contenteditable="false"]

It is admittedly a bit beyond "easy customizability" once you find yourself sifting through element attributes in the dev console to craft a selector ("easy" shouldn't require knowing what any of those things are, I would think), but in case you still want to actually do it, this seems to work.

They have an ungodly number of event listeners. Why do they need so many? And I keep finding spans nested inside spans for no reason; i.e., the parent span only contains a child span. It's such an outrageous mess

I never see any "Press / for.." or anything like that. I rejected all the 'smart' features when gmail one day popped up an announcement about them.

From this I can infer you are not using Chrome (the source of those can't be disabled prompts).

That's correct - I've never used Chrome, I've used Chromium but not now. I'm using gmail with Vivaldi (chrome-based) and Firefox.