I've owned three Jaycos. Two were Designer 5th wheels with gelcoated fiberglass sidewalls. Neither of these experienced any delamination problems, nor am I aware of delamination being a recurring problem with Jayco RVs.
Without photos and/or additional information, I wouldn't speculate on the underlying mechanism behind your delamination problem.
In searching the forums for "Jayco delamination", the only other reference I found was HERE
2016 Ram Longhorn 3500 Dually 4x4 CCLB, 385/900 Cummins, Aisin AS69RC, 4.10
2014.5 DRV Mobile Suites 38RSSA #6972
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