Transparency without blur effect

We need to find which property is applying the blur (Maybe it is in your theme, or an obsidian default). Use the inspector to check where the blur is being applied:

Another guess:

.theme-light .workspace {
    backdrop-filter: none!important;
    background-color: transparent;
}
.theme-dark .workspace {
    backdrop-filter: none!important; 
    background-color: transparent;
}

body { 
    --background-primary: transparent;
    --background-secondary: transparent;
}