What's wrong with variables in create-react-app that don't work?

the address of the test environment was accessed after npm run build. Why are the variables not parsed here?

Aug.23,2021

I'm afraid I'm going to visit the template html, not the html. from build

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b22527-2b5ff.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b22527-2b5ff.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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