What is the name of an "interrruption screen" element in the middle of an anime episode?
In Japan, the term is called eyecatch, which is also known as bumper. As the question has mentioned, it's usually to indicate the start and end of the commercial break.

In broadcasting, a commercial bumper, ident bumper or break-bumper (often shortened to bump) is a brief announcement, usually two to fifteen seconds in length that can contain a voice over, placed between a pause in the program and its commercial break, and vice versa.

In Japan, an eyecatch (アイキャッチ aikyatchi) or internal eyecatch is a scene or illustration used to begin and end a commercial break in a television program, especially in anime and tokusatsu shows. The term is used, in Japan, to refer to all kinds of bumpers.
In many television series, eyecatches are contemporaneous into the climax of a story, leading onto speculation during the commercial break.
Unlike in American programs, in which bumpers are typically supplied by the network (when they have them at all), eyecatches are almost always produced by the production company and considered a part of the program itself, rather than (or also serving as) a segue into a commercial break. They are typically two to six seconds in length. Eyecatches for children's programs are often longer and more elaborate, while eyecatches for programming intended for adults may consist of nothing more than the program's logo against a black background.