@solidsanek Looking at the source code which hides the play icon:

```
:root[uidensity="compact"] .tab-icon-stack:not([pinned], [sharing], [crashed]):is([soundplaying], [muted], [activemedia-blocked]) > :not(.tab-icon-overlay),
#tabbrowser-tabs[secondarytext-unsupported] .tab-icon-stack:not([pinned], [sharing], [crashed]):is([soundplaying], [muted], [activemedia-blocked]) > :not(.tab-icon-overlay),
:root:not([uidensity="compact"])
#tabbrowser-tabs:not([secondarytext-unsupported]) .tabbrowser-tab:not(:hover) .tab-icon-overlay:not([pinned], [sharing], [crashed]):is([soundplaying], [muted], [activemedia-blocked]),
:root:not([uidensity="compact"])
#tabbrowser-tabs:not([secondarytext-unsupported]) .tabbrowser-tab:hover .tab-icon-stack:not([pinned], [sharing], [crashed]):is([soundplaying], [muted], [activemedia-blocked]) > :not(.tab-icon-overlay) {
opacity: 0;
}
```

you can run this on your UI to get compact mode: `document.querySelector(':root').setAttribute('uidensity', 'compact')`

for a permanent solution you can go to about:config and set `
browser.compactmode.show true` and select compact mode in the customisation.