Depends on if they have contracts or not.
For example if in the style had a contract saying they were going to create say 3 collaboration collections with her, they'd need to write to her and state that they wish to dissolve the contract.
If a brand haven't officially stated in writing that they will work with her on x date they don't need to do anything as they'll class it as hearsay.
If a company has said we will like to work with you in 2022 but didn't send her a full proposition yet, they will still need to contact her to state they will not be working with her this year as in a court she could argue there was an agreement in writing for them to work together at some point this year.
A lot of companies have a clause that states that of the actions of their clients could affect the companies name/brand/safety of staff etc, they reserve the right to dissolve any contracts