Rated 4 out of 5 stars

And I can not see two colors (for example, gradient left to right) - both calendar and category?

This review is for a previous version of the add-on (4.0).  This user has other reviews of this add-on.

Coloring event with category color

If the "Apply category color to event backgrounds" option is enabled, the calendar color is no longer shown on events. If this option is disabled, the event background color is the calendar color and there is a small category color box (i.e. exactly as with normal Lightning).

It would be possible to develop a new version of Calendar Tweaks, so that when the "Apply category color to event backgrounds" option is enabled, the event background color would be the category color and there would also be a small calendar color box. Would this meet your needs?