Wrong block appender button showing

Question

I noticed when creating a fresh site block appender button looks cleaner than my other site. This is a fresh site:

This is my other site (big rectangle button):

I disabled all plugins and switched theme to twenty-twenty to test. Still looks wrong:

I made sure no plugins are active, no mu-plugins, no additional CSS, and switched to twenty-twenty-three. When I create post, it still looks like the rectangle button. Am I missing something that would make it look like that?

Thanks!

Answer 1

There are two default types of appender buttons and those two are them. Either you inserted some block like columns which uses this appender in second case, but you are not aware of it, or you have some software like plugin or theme which tweaks appender button.