The comment line breaks the command continuation in Bash. The backslash \ at the end of a line continues the command to the next non-empty, non-comment line. Since # Test is a comment, ca-certificates is interpreted as a separate command.
Fix: Move the comment to the end of a line with a continuation or another argument:
apt install \
htop \ # Test
ca-certificates
or
apt install \
htop \
ca-certificates # Test