OldThink/Content.Client/Message/RichTextLabelExt.cs

using Robust.Client.UserInterface.Controls;
using Robust.Shared.Utility;

namespace Content.Client.Message;

public static class RichTextLabelExt
{
    public static RichTextLabel SetMarkup(this RichTextLabel label, string markup)
    {
        label.SetMessage(FormattedMessage.FromMarkup(markup));
        return label;
    }
}