Yes of course your partner should give you a heads up about a permanent change to arrangements. And I know you've said you didn't mean you wanted permission, but actually it should have been a family discussion before being agreed anyway.
When lockdown happened - we needed to work out what would happen with home schooling my SDs. ExW was chopping and changing each week which was causing mayhem, and she was also nudging towards us homeschooling every day, with no overnights and no weekend contact time (don't even get me started).
DH and I agreed that we we needed a regular weekly schedule (though obviously we could flex for emergencies).
He initially thought of three days for us to have them, which he thought would have worked. I said: ooooh, actually Tuesdays are a nightmare for me because of X work reason, what if we do these three days instead - with this day overnight.
Him: oops forgot that, yes let's suggest those three days - and the overnight is a good idea. So that's what we did. ExW knew we would cover if she had any important meetings but that Tuesdays were a no except for emergencies. It meant that we could all keep working and vaguely try and educate the children at the same time.
That's how it should be for ANY major and permanent change to how the access schedule works.
Everyone saying that it's the children's home and they should be able to come whenever they want is being totally disingenuous - because in op's scenario the children's didn't ask - the ExW did.
In our house, if the girls ever ask if they can come over or stay longer our response is automatically - of course you can come whenever you want - it's your home, but just make sure mum is happy with it (because it's not fair for us to dick around with her days with them, so they need HER permission). Unless we have set in stone plans, in which case we either offer to involve them, or suggest another day / time instead if the plans aren't child friendly.
On the other hand, if ExW wants us to have them as a one off to help her out, DH says: almost certainly fine but let me double check with Once. (If we are free it is fine and I would never say no to extra contact, but sometimes I / we may have plans). This he absolutely will run by me.
This isn't making the kids feel like it's not their home, as they are not involved in these conversations. It does however help set boundaries with ExW and make it clear that she cannot just automatically dictate.
If there was a major permanent change to the arrangements - we would discuss it. The starting point would be: yes great to have more time with the kids. But the end point would be do the actual days work well.
For instance, like OP I do all the cooking (but none of the cleaning). On Wednesdays I have a bridge night. So if the new arrangement was Wednesdays - I'd say - ok - but don't forget I have (currently virtual) Bridge that night.
DH might say: that's perfect, we can have daddy daughter time and I'll cook. Or he might say: actually it's a bit weird if every week they're here you're squirrelled up in your room on the laptop so let's counter-suggest that we do Thursdays instead. Etc etc. He'd never agree to a new permanent set up without discussing it with me first. And I'd be highly unimpressed if he was kowtowing and prioritising what worked for ExW over what worked for us (including me) and the girls.