Well, I don't use Gnome3. I use LXQT, with PekWM and Compton.
However, due to the plug and play way of LXQT, I can tell you how to "maybe" fix it. For me, this is Compton. Simply running it gives Tilda transparency (at least, if you set it as such in Tilda's settings.
At the very least it is worth trying out.
[Copypasta from post for OP]
Well, I don't use Gnome3. I use LXQT, with PekWM and Compton.
However, due to the plug and play way of LXQT, I can tell you how to "maybe" fix it. For me, this is Compton. Simply running it gives Tilda transparency (at least, if you set it as such in Tilda's settings.
At the very least it is worth trying out.