Here's the subject line field:
<input type="text" id="TextField2091" class="ms-TextField-field field-257" maxlength="255" autocomplete="off" spellcheck="true" placeholder="Add a subject" aria-label="Add a subject" aria-invalid="false" value="">
The generated rule is probably using the id for the Name, which can have a different number every time you reload the page. Try changing the Name in the rule to this:
^Add a subject$
On Thursday, February 3, 2022 at 4:45:17 AM UTC-8 Naravno Nije wrote: