The actual size of bootstrap3.3.7 is 121kb, why do some websites actually request only 26kb?

the size of the requested bootstrap.min.css on the bootstrap official website is only 23.6kb, but the actual size of this file is more than 120kb, including the Compiled and minified CSS downloaded from the official website.
bootstrap bootstrap.min.css

bootstrap.min.css

121kb

how can this website only have 23.6kb when requesting a server?

Mar.04,2021

it is estimated that gzip is enabled on web server

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