Frequently, well-meaning priests are inserting “all” into the words of absolution, as in “I absolve you from ALL your sins.” Is this enough to invalidate the absolution? I have experienced this many times over the years with different priests.
No, the introduction of “all” as in “all your sins” does NOT invalidate the absolution.
However, the very fact that you ask this question raises the deeper problem.
When priests (yes yes… and deacons) screw around with the texts of sacred rites, they run the risk of
a) doing something invalid,
b) doing something illicit and/or
c) confusing or even scaring the people they are ordained to serve.
We have seen recently the drastic consequences down the line, even years later, when some jackass screws around with the form of the sacrament of Baptism. Consider those priests who had to be baptized, confirmed, ordained years after the fact of their invalid baptism.
When people hear from priests or deacons some strange or cobbled up prayer or form for a sacrament, quite often alarm bells ring for them.
This happens in confessionals.
Priests, thinking they are being “meaningful” or “deep” goof around with the words of absolution and, thereby, create confusion in the minds of those lay people who know what the form of absolution is and how important it is to get it right.
Moreover, in that moment of sacramental confession, people are at their most vulnerable and their souls are acutely tuned to the significance of the action.
Fathers… don’t be jackasses. Don’t make things up. Don’t hurt people.
Stick to the texts!