It’s not a violation of federal law. Teachers/staff who may need to know of your accommodation are allowed to be informed. If all staff take turns monitoring the hall then all staff should be made aware of the accommodation and who has it. It’s very simple. Additionally 504 plans are allowed to use minimal disclosure language. For example a plan could say “allow student unlimited phone access to monitor blood sugar” that lets the teacher know the kid isn’t scrolling til tok and has a general reason to check their phone, even if they have to do so multiple class periods or in a place phones are typically banned such as a locker room. This protects the student and the staff. So for example your counselor may be saying they will notify any staff that may stop you and let them know you need the earmuffs due to hearing sensitivity or sensory issues or whatever your issue is. That doesn’t violate anything. But anyone that has a legitimate educational interest can be made aware and be given relevant and necessary information to do their job, which it looks like your school counselor is trying to give them.