This list includes all films. It's just that horror movies have been historically the most formulaic to make on a low budget.
Not yet in order of importance.
A further list might be derived from this, which I may call something like, "The Old Formulas Don't Work Anymore."
Instead of saying this every time I'll say it here: "...or maybe it's just me getting old and cranky." Just go ahead and add that to the end of each item.
Also, as in rules for writing English, there is ALWAYS an exception.
1. People talking at a far distance from the camera, yet we hear their dialogue. They're usually walking, driving or sometimes it's a montage scene. This is obviously to save money, since the audio doesn't have to be synched even in digital post, nor does the audio crew need to focus on staying out of the shot, nor does the audio have to be recorded on site. It could be recorded in a studio or just on a different day. For me, this destroys the suspension of disbelief.
2. Talking Heads. Great band. Unfortunately, we're not talking about them. The band's name is a somewhat derogatory euphemism for a news reporter, specifically an anchor person, of whom we only see their head in a close up or at least chest up. It is part of the classic low budget film formula, throw two people, chest up or more, and have them talk. One scene like this in a movie can drag the film down, and some low budget filmmakers have several talking head scenes.
3. Small Fonts. Modern fonts that were made for the big screen but can't be read on the modern small screen, even a regular television, yet alone a tablet or phone.