VS2022, VS2026 winforms designer for .net framework wants to load System.Runtime.dll v. 10.0.0.0

sorry, there wasn't a issue template for the .net framework winforms designer, so i create this blank one.
here's a screenshot of the stacktrace.

here's a link to the devcom issue we created yesterday:_
https://developercommunity.visualstudio.com/t/winforms-net48-designer-fails-to-load-S/11001203?port=1026&fsid=38f24fd5-33b2-4177-974d-62cb0c6993f4

We suspect it's because we have properties on the base form (that gets instanciated) where the types are coming from netstandard 2.0 assemblies or ones that are multitargeting both net10.0 and net48,
We think that, because in one specific case, the error goes away if we uncomment a certain property. sadly, that doesn't work for most of our forms. (see the linked devcom issues for details)

Is there a way to debug into the FilterApplyMethodsBase call, by any chance?

i remember, back in the day, you could attach a second VS and sometimes make progress there. why isn't that possible, here?