The last two years yes they did seed beta 3 seeds and do the PB seed a week later after providing an update seed at the same time to devs.
It's just the way the dev iOS/IPadOS 18 releases are working along with the end of profiles and just using Apple ID aka Apple account now, with as previously mentioned anyone can sign up for the dev seeds via Apple developer site, they really don't need to delay the PB seeding for a week. These last few iOS 17.x seeds have been less problematic then previous years. Also if something is found they can act immediately and rerelease beta 3 or PB1 anytime they want. It's not like Apple needs to tiptoe as much as they used to with PB being so good, when they have several betas to go before it goes public in Sept.
Also both the dev seeds occurred on a Monday. When has that ever happened before.