The current situation in the USA made me wonder whether something similar could happen in the Order for inter-covenant arcane trade (e.g. books, vis, enchanted devices). Note that tariffs on mundane stuff are a big deal in mundane Mythic Europe (see smuggling in C&G), but I am not aware of anything of the kind affecting inter-covenant arcane trade. Some story seeds:
Make Thebes Greek Again! The Tribunal of Thebes. worried about Greek losing footing as the official language in the Tribunal, decides to tax any import of books written in Latin.
Make Enchantments Great Again! The Primus of House Verditius wants the enchanted device trade to become a monopoly of House Verditius; so he lobbies the Order to rule that any trade in Hermetic enchanted devices must involve a Verditius venditor either as the buyer of the seller. He bullies any *cheating, unsupportive" covenant with a vis tariff of 145% on all items purchased from House Verditius.
Make Vis Ours Again! The leader of your powerful, autumn covenant claims that it is too reliant on vis obtained in trade from other covenants, and has seen its own vis sources dwindle as a result. So he imposes a heavy tax on any vis obtained by the covenant's magi, except for that harvested from the covenant's own sources or extracted from the covenant's Aura.
The first might well be possible, just a matter of gaining support.
The second has a better than 50/50 chance of resulting in the rest of the Order buying less (or even no) Verditius goods. He would also likely end up charged multiple times before the Tribunal with attempting to steal the magic of other members. Heck, once the first one or two are filed there would be a pile on that could bankrupt the whole House.
The third is asking for trouble. Unless it is in the Covenant charter, there is a decent chance that an overthrow attempt happens. Also taking vis from others 'on his say so' is stealing their magic, thus charge before the Tribunal.
The difference between the first and the other two is that the first is a collective agreement, while the other two are forced attempts by a single (or even small group of) Magi. Unless your Order is a lot more of an actual government and less of a social group, they would most likely react very poorly to another Magi attempting to forcefully take from them.
Well, I think it's perfectly realistic that tariffs might not actually work as intended/claimed by those devising them Interesting complications are a feature, not a bug. At least in the game...
Oh I wasn't trying to say not to have someone attempt it in game, just that it would have some very unexpected effects given how independent many Magi are. It would lead to some interesting games for sure.
In Against the Dark, there are story seeds involving the Tremere controlling the magical economy of Transylvania. In most parts of Mythic Europe, this is unlikely to work because many covenants are staunchly independent and buy as little from other covenants as they can get away with. If you make trade with you too difficult or expensive, other covenants will just stop trading with you and try to bypass you. If you have something that you do better than anyone else (like Venetian glassware or Byzantine silk) then people will come to you and you can command a good price.
Interesting complications are a feature, not a bug. At least in the game...