Unable to exit Speedreader mode/disable Speedreader

Description

Unable to exit Speedreader mode/disable Speedreader

Steps to Reproduce

1. new profile
2. launch Brave
3. load https://www.reuters.com/technology/cryptocurrencies-selloff-widens-bitcoin-down-nearly-4-ether-6-2021-09-07/
4. click on the Reader Mode icon in the URL bar
5. click to enable Speedreader
6. now, click on the Speedreader icon again

Expected:

The page exits Speedreader/Reader Mode, and returns to “full” HTML mode rendering

Actual:

Even though it appears I’ve toggled reader mode to Off/Disabled, it persists for this tab

Reproduces how often:

100%

Brave version (brave://version info)

Brave	1.31.27 Chromium: 93.0.4577.63 (Official Build) nightly (x86_64)
Revision	ff5c0da2ec0adeaed5550e6c7e98417dac77d98a-refs/branch-heads/4577@{#1135}
OS	macOS Version 11.5.2 (Build 20G95)

/cc @keur

[keur]

Test Plan

Ensure the per-site toggle works as expected. Thanks @stephendonner !

[keur]

Added release-notes/exclude since this bug hasn’t made it out of nightly.