Protective equipment laws in most team sports come down to one official's judgement at the tunnel, with no standard, no gauge and no appeal.
A referee decides whether your brace is legal, and that is a strange job
The law usually says something like this: the referee shall not permit equipment considered dangerous to another player. That is the whole test. No thickness, no material specification, no approved list in most codes, just a person making a call about a splint they have never seen before, ninety seconds before kick-off, with both coaches watching.
I have watched two officials reach opposite conclusions about functionally identical wrist casts in the same competition inside a month. Neither was wrong under the law, which is exactly the problem. A standard that is entirely discretionary is not a standard. It is a lottery whose ticket is the temperament of whoever got the appointment.
The consequences run in both directions and both are bad. Players who need genuine protection to return get turned away, and the workaround is to pad the cast until it is soft enough to pass, which frequently makes it worse at the job it exists to do. Meanwhile a hard shell under a sleeve, unmentioned and unnoticed, goes on the field every weekend because nobody checked. The rule punishes disclosure. Anyone who has managed a returning player knows the tunnel conversation is a negotiation, and the ones who lose it are the ones who ask first.
Face guards have the same trouble. So do knee braces with metal hinges, and increasingly the compression sleeves with rigid inserts that sit in an equipment category nobody drafted for. Governing bodies keep responding with circulars rather than law changes, which leaves the referee holding a memo they may or may not have read.
What I want is dull and achievable. A published specification with numbers in it. A certification that travels with the player rather than being re-argued every week, issued by the competition medical officer and valid for the duration of the injury. If a device passes once it should pass everywhere in that competition, and if it fails it should fail with a written reason the club can address.
Until then, officials are being asked to perform an engineering assessment on the spot, in a role that gives them no training for it and no cover if they get it wrong. They should refuse. Not the fixture, the responsibility.

