Question: How to replace multiple dots in file name only ignoring file extension?

[r4dh4l]

Hi,

I would like to replace/remove multiple . in a file name like test1.test2.test3.test4.flac.

I started with rnm -rs '/\.//g' ./* which replaces every . but the result is test1test2test3test4flac.
Then I tried rnm -rs '//n/./_/' ./* but this replaces the whole file name with an underscore so the result is _flac.

In this context I think the chapter https://neurobin.org/docs/unix/rnm/bulk-rename-in-linux/#12-applying-uppercase-lowercase-conversion-on-filenames-partially is a little bit misleading for me:

Now, lets change the case of filenames without the extensions, i.e .jpg, .png should be intact. To do that we will have to select the part before the last . and replace it ...

But rnm -rs '/.*\./_/' ./* replaces the whole file name except the extension. So maybe the quoted sentence should not say "the last ." but only "the .".

However: Is it possible to remove multiple dots in the file name without the extension dot?