I’d quarantine them as long as you see fit, which is usually a balancing point between how long you want to babysit a qt tank before you risk throwing them in the main
If your quarantine tank is basically just a box of water, you’re going to see some strange behaviour. If it’s a fully decorated tank with substrate and the whole ball of wax, and they’re still acting funny. I would hold them in there for a while yet before I risked putting them in general population.
Sometimes they just take some time to adjust to their new surroundings and water conditions, sometimes it’s more than that! I would hold them for probably another week in that tank before considering moving them depending on the risk level of the main tank. In the case of most ‘expensive’ tanks, it’s not uncommon to quarantine new fish for months before putting them in the main tank. Even if it’s a $300 fish, that doesn’t make it free from parasites and disease and you certainty don’t want to risk several thousand dollars of livestock in the tank! But even on the smaller scale, with ‘cheap’ fish it’s easy to have a lot more money in livestock in the tank than you want to risk over a couple new fish