Slack icon not displaying properly on Windows Buttons

Hello, so far everything works beatifully with xfce4-panel 4.16.2 (Xfce 4.16), however the icon for Slack seems to be wrongly rendered.

This does not causes any issue in functionality but I thought it would be nice that it got fixed.

Tested in Xubuntu 21.04, Slack 4.19.2 from Snap

Thank you