Bugzilla

It's not completely possible to reproduce the bug as described. 
On http://softbooker.reservit.com/reservit/reserhotel.php?lang=FR&hotelid=200568 
the autofill works for creditcard number and for part of the expiry field. It fills in only the month for a field that should be filled with month and year. That seems to be happening because the input field has an autocomplete attribute set to "section-cc cc-exp-month", so the inferred field type is cc-exp-month instead of cc-exp. For this case, when there is only one expiry field, and it has the value cc-exp*, the fieldname should be updated from cc-exp* to cc-exp at this line of code: https://searchfox.org/mozilla-central/source/toolkit/components/formautofill/shared/FormAutofillHeuristics.sys.mjs#394 
However, the updateFunction returns without updating because of ignoreAutocomplete=false: https://searchfox.org/mozilla-central/source/toolkit/components/formautofill/shared/FieldScanner.sys.mjs#265

It's not completely possible to reproduce the bug as described. 
On http://softbooker.reservit.com/reservit/reserhotel.php?lang=FR&hotelid=200568 
the autofill works for creditcard number and for part of the expiry field. It fills in only the month for a field that should be filled with month and year. That seems to be happening because the input field has an autocomplete attribute set to "section-cc cc-exp-month", so the inferred field type is cc-exp-month instead of cc-exp. For this case, when there is only one expiry field, and it has the value cc-exp*, the fieldname should be updated from cc-exp* to cc-exp at this line of code: https://searchfox.org/mozilla-central/source/toolkit/components/formautofill/shared/FormAutofillHeuristics.sys.mjs#394 
However, the updateFunction returns without updating because of ignoreAutocomplete=false and the fieldDetail.reason == "autocomplete" : https://searchfox.org/mozilla-central/source/toolkit/components/formautofill/shared/FieldScanner.sys.mjs#265, 
which is desired behavior.