its been a longstanding rule on the forums even in its early years. while it may seem imbalanced its one folks have had to adhere to like it or not.
people are allowed to say that they are seeking artists but comission promotion or solicitation of most types has been disallowed and as far as i remember theres not much workaround except maybe doing that promo on the discord since it seems to be permitted there
the primary use of the forums, as i saw it, has always been for networking and community building: talking to fellow creators or readers on tapas. the promotion thing is somethig that has existed but exploded in some pretty one sided ways but we manage.
like leyele mentioned tho its best to just seek out alternative places to promote your commissions than trying to war it out with any moderators here on the forums. as i mentioned i /think/ the tapas discord allows for such promotions in the proper channels and pretty much any social media (ie twitter instagram bluesky etc)
about the only semi successful workaround ive seen were threads that made it a gathering place for everyone to contribute, like "artists post your commissions here" or "share your meberships (if you have kofi or patreon)" im sure most of those have long since been archived since they're years old but i definitely remember them existing at some point or another
otherwise not much option than to just accept the rules and work with whats available 🤷🏾
edit: also wanna add that im saying this as someone who also complained about it early on but still managed to find alternatives. like if youre really itching to get your art out there along with services you offer try posting to the sketch a day threads or post your latest chapter/page/panel threads and have links to your other sites (social media, tip jars, etc) in your bio (check the settings tab) so that if someone digs your style and their curious they can find it all there. its how i managed to find a few clients here and there beyond just those "looking for artists (paid/unpaid)" threads.