Hyprland opacity rule not working for Thorium

I'm trying to change the opacity of the Thorium web browser in Hyprland by adding

windowrulev2 = opacity 0.80 0.80,class:^(thorium-browser)$

to the configuration file, but it's not working. This same rule works for Thunderbird, so I'm not sure what's wrong.

Any tips on what I might be missing? Is it possible that Thorium simply doesn't support transparency, or am I doing something wrong? I'm not sure what to do next, and I'd appreciate any help you can offer. Thanks!