Too Much Information. A written form of verbal diarrhea. Unnecessary detail can distract the reader from your plot and story.
While there are successful authors that have what objectively could be called excessive prose, they’re rare. And, generally, if you look at their earliest work it’s much more tight and condensed.
The general rule of thumb is the importance of everything is proportional to the words used to describe. So when you mention, for instance, a 21 inch Dell monitor or an iPhone XS (note that doing so dates you), that detail is presumed to be important and a reader will tuck that away for future reference. When you fail to pay off that investment, you break that trust and they start to skim, not feeling there’s value in your detail. It’s exactly like Chekhov’s gun:
“Remove everything that has no relevance to the story. If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it’s not going to be fired, it shouldn’t be hanging there.”
“One must never place a loaded rifle on the stage if it isn’t going to go off. It’s wrong to make promises you don’t mean to keep.”
“If in the first act you have hung a pistol on the wall, then in the following one it should be fired. Otherwise don’t put it there.”
You can, of course, go too far in the opposite direction and not provide enough detail for the reader. This is always a balancing act and akin to the tradeoffs on showing vs telling. I tend to lean on the side of less is more and trust to my reader’s imagination. I believe that’s one reason why I felt drawn to screenplays, they deliberately want only enough description to evoke a sense of place. But novels readers want more than a sketch of place, they want rich details.
How much is too much? I believe it’s when you provide something that stands out from the writing with it’s detail, like the above mentioned Dell 21 inch monitor (why Dell? Why 21 inch? Even ‘monitor’ is potentially a detail that would stick out). Is that detail going to be referenced later? If not, then it’s important to consider whether you’re going to distract your reader. Sometimes the detail helps set the scene, so this is not a blanket condemnation to remove it all. But always weigh what you’re seeking to achieve with your story with the irrelevant detail you provide.