If we'd have known about it in ETS we would have tested it or even objected to the change from the start. The first one to have noticed it on the community was Russel W. but only after the release (he's also an ETS tester).
I think most versions are released 3 -4 weeks after its build-date, so nothing unusual there. But it would be a good idea if next time the list of 400 or so fixes are published as well, so we can check everything 
As you describe this issue, I can’t help but remember when versions prior to 16 used to cause trouble with Outlook when FileMaker was installed (64 bits) on clients that were 32 bits OS. Three symptoms were that it would throw into a loop when generating the email, or the attachment seemed to be there but it would send a blank pdf, or FileMaker crashed.
That also happened on 64-bit Windows-clients with a 32-bit MS-office installed and the installed FMP is 64-bit. Use send-email-with-client and FileMaker hangs forever.
I have not seen this for a while to be honest, but I expect this still is a problem when an older (32-bit) version of office is installed.
The problem with quote() is not secluded to creating emails though. The core of the issue is that quote() doesn't translate CRLF correct. You can check that very easy in any db with some containerfield with some file/image etc. in it:
Let ( [
base64data = Base64Encode ( Container )
] ;
base64data = Evaluate ( Quote ( base64data ) )
)
The calculation should return: 1 but only in version 19.5.1 it returns 0.
This means that quote changes your data and if you use quote to wrap data, to later evaluate() back to original, you'll never get your original data back. I can't speak for everyone, but I suppose a lot of use quote to wrap data into some handy format to move variable around etc. So this problem touches a lot of our solutions.
A 'Quote' function that modifies the quoted data is a strange animal.
Absolutely, Gowan was signing "You're a strange animal, ..." 
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