SharePoint pageload suddenly breaks when using `List` and/or `RootFolder` querystrings

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

not applicable

Developer environment

None

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

Describe the bug / error

I'm seeing very odd problems when loading pages today.

For example: I'm having a very basis empty page here:

If I add the querystring ?List=43355f7d-c021-4317-9d05-92cece2a1553 (With some random GUID), the page loads badly:

If I add the querystring ?List=someirrelevantvalue&RootFolder=/sites/hr, the page breaks with a message saying it cant find items.

If I add the querystrings ?List=c71dde57-82e9-4210-b856-c5347e63f298&RootFolder=/sites/hr/documents which are referring to an actual document library on another site, the page crashes in another way: saying it cant get a property Title from an undefined object.

This is all quite strange. It seems Microsoft has implemented some new behavior around these two query parameters. Or it's just one code path that now suddenly breaks.

But on our end this breaks a customer solution, because we use NewFormUrl's on content types to redirect to customized creation pages, on which these parameters are added by SharePoint and then the page breaks, blocking people from creating stuff.

Is there someone who recognises this? It's behavior across tenants.

Steps to reproduce

Just append ?List=<some-guid>&RootFolder=/sites/site-url to the URL of your page. (just after .aspx

Expected behavior

It should not crash...