The last version where scaling of arrow heads was working fine was Indesign 2018.2. The error occured starting with Indesign 2019. It is discussed in the Adobe community here https://community.adobe.com/t5/indesign-discussions/stroke-start-end-scaling-not-working-in-indesign-when-the-stroke-weight-is-below-1pt/td-p/10495516 .
This error is now arround for about FOUR years.
I was on a chat with Adobe support today (May 2023) and the support guy was able to reproduce the error on his system. He recommended to "vote for fixing this error here on uservoice.com" . It is hard to believe Adobe still want us to vote about "does it really bother you, if Indesign does not behave as described in the manual?", instead of simply fixing an error that should not be existing.
As much as I love new functions being added to Indesign, I also would appreciate if Adobe would keep an eye on maintaining reliability of prevoiusly developed functions.

Super annoying when Illustrator interface works perfectly while InDesign isn't.

Not sure of the exact measurements but it seems like you can only get the arrowhead about 20% bigger or smaller than the default, no matter what percentage you put in. I've gone back to lines and triangles when I need something that looks different.

It's super annoying that you can't use a smaller triangle arrowhead for a 1pt line.

and

While using the SimpleWide arrowhead I can't imagine anyone wanting the line width of the arrow head to change, just the length of the arrowhead lines.

And while talking about arrowheads, let us create custom arrowheads.

(InDesign 16.2.1 on Catalina)

I am having the exact same problem. This is really interfering with my ability to create flow charts in InDesign. Please, please fix this bug!

Same problem here.

I think the rendering of scaled arrowheads is correct in Illustrator bu not in InDesign.

See screenshot for comparison;