BroadcastChannel enters Baseline in 14th of September this year (30 months since support in all major browsers). The other major ones except Safari had this in 2015-2017, but Safari added it in 2022, sigh. But it's becoming Baseline now!

This could be used to close and give cookie consent in all open tabs when consent is given in one. If for example user happens to open multiple pages from Google or just doesn't give consent but opens multiple product pages to a new tab, it can be a bit annoying to close cookies in every one.