When the core for check-spelling was initially developed, it was a lot simpler and didn't have any support for patterns.
As it was often run against C/C++ repositories, code was baked-in to handle \n, \r, and \t.
If you're currently working around that special casing, you'll be able to remove your patterns.txt entries for them.
If you're currently relying on that special casing, you'll need to add entries to patterns.txt, something like:
(?<!\\)\\[nrt]
Expecting to deploy in v0.0.22
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