There are numerous questions as to why any cannot be narrowed from. Despite being natural and intuitive this feature was rejected due to being a serious breaking change to poorly written yet massive code bases.

Please consider putting it behind a flag provided the evident need for it.

TLDR

• any is not what you think it is (poor naming at play)
• for narrowing use type unknown = {} | undefined | null | void instead
• yes, it's a hot unfortunate mess
• no, there is no painless way to fix it
• yes, you gonna need to fix your *.d.ts by hands
• why? to make average JS developers happy with their less than perfect code
• welcome to the club! get your badge at the reception

UPDATE
@yortus made a branch per #9999 (comment) where narrowing from any works!

try it: npm install typescript-narrowany