If you search and not browse and find assets of those users, maybe they are what you are looking for. If it is single user, use find in page function of browser to highlight and ignore user.
Or go fullignore with a user style with Stylus extension. Tested with Crhome. But you might not see anything from that user in your library, so maybe use better url filter than domain.
@-moz-document domain("itch.io") {
div.game_cell:has(a[href*="//username1.itch"] ) { display: none }
div.game_cell:has(a[href*="//username2.itch"] ) { display: none }
}