The code which removed the background image of a snippet when choosing a
background color worked kinda by chance. Indeed, on the final click on
the color option, the snippet background-image was reset... to the
current background-image, which is none thanks to the color preview.
Unfortunately, in some themes, the gradient color option interferes:
the current background-image at a color choice is equal to the current
gradient, and thus, that gradient is being moved as an inline style.
The bug was introduced with https://github.com/odoo/odoo/commit/285d95e946e5a15139c961e30dbe3598e0d99f6a
(as, before, the background reset was done by simulating a click on the
'background: none' option item, which was removed).
Closes https://github.com/odoo/odoo/pull/27808
qsm-odoo
a9f11fb477