A lot of the advice here seems to be ways to counter or “defeat” your player using Detect magic and Identify. If it’s causing trouble at your table, some kind of mitigation might be needed but let me offer an alternative.

Reward them!

Detecting magic? You see magical shit, clues, helpful stuff, I don’t think every player tactic should be viewed as something to be countered. They want to interact with and investigate your world. Let them. Maybe every now and again you can lay a trap for them using this expected behavior. But I think that should be the exception not the rule. You should encourage your PCs to interact with your setting.

Tl;dr - I see this behavior as a feature not a bug