MLS does not determine the rules for such competitions; FIFA does. There were no pertinent results (archived here) from a thorough search of the FIFA website.
For rules governing the 2025 Club World Cup that would have specified which emblems will be prohibited during the competition.
The 2024 FIFA legal handbook, which is available here, states that “all associations and clubs are liable for inappropriate behaviour on the part of one or more of their supporters”
When those supporters use “the use of gestures, words, objects, or any other means to transmit a message that is not appropriate for a sports event, particularly messages that are of a political, ideological, religious, or offensive nature.”
“Political, religious, or personal messages or slogans of any nature in any language or form by players and officials” are also prohibited.
The same guide states that “FIFA is committed to respecting all internationally recognized human rights and shall strive to promote the protection of these rights.”
