Like maratsade, I would suggest checking out reader view type extensions for Firefox. I don't use Firefox, but I've no doubt they have a few like that. This way you can more or less "force" a reader view on demand if the built in one doesn't give you the option to enable it on certain pages.
Ryzen 5 3400G | MSI B450M Pro-M2 MAX | 16GB Corsair Vengeance DDR4 3000 | XPG SX8200 Pro 512GB NVMe | Windows 10 Pro
