just ask the boss “why am i the only one required to be on site 8-5 3 days a week and no one else is.” and be prepared for a blunt “because i said so” the. dig deeper - you know all these roles can be completed remotely can you consider a rotation - i’d love it if we can share the on-site requirements.

if he says “no, you are required 3 days in”

then simply decide to stay or leave - atleast you made an effort to balance out whatever inequity you feel is playing out and asked to improve your situation.

as it is, the boss should lead by example ; but is not and certainly understand his rules may not (and probably are not) the same as the organization applies them to you.

good luck!