Tilted gallery flickering after upgrading to WP9

Hello, After upgrading to WP9, the right panel for tilted galleries I use on almost every page started to flicker. When I change the theme to the default Twenty Twenty One, the display is fine. I renewed my licence for the theme, thinking it might help, but this has not solved the issue. WP support also couldn't find an answer to this. It only flickers in Firefox, MS Edge display is OK. Could you help me with this, maybe it has been reported by other users. Best regards, Anna