I cannot confirm this.
I did not know this software but before answering I tested it and after resizing the file-size and the tagsize became smaller.
Did you perhaps set the quality to 100 %? The usual compression of JPGs is about 80% and if you resize only a little but set the quality of such a conversion to 100% the size may even get larger.
Setting the quality to 100% enlarges the jpgs
There may be also some rare cases where padding matters.
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