I am using bash on Lubuntu 20.04 LTS, but I get an error using the rename command.

symptoms
Installed the rename command with apt-get on the Lubuntu 20.04 LTS bash.Then, when I ran the following command so that the file extension is .sh and the extension is .txt, I got an error.

$rename.sh.txt*.sh
syntax error at (user-supplied code), near ".""

Also, when I tried running without ., I got a message from Bareword~.

$renamesh txt*sh
Bareword "sh" not allowed while" strict subs" in use at (user-supplied code).

Expectations
I would like to convert all extensions of .sh files to .txt.

Reproduction Steps

$sudo apt-get install rename
$ rename.sh.txt*.sh
$ $rename sh txt*sh