My 2018 Jay Flight is the same and I don't like it.
What I did was trimmed a couple pool noodles for a snug fit underneath the slide's raised floor, running the full length. That way if I step on the slide's flooring when loading/unloading the TT I won't damage the "thin" plywood flooring.
My prior Eagle's slide floor had a much thicker flooring material and the gap was minimal....., never was an issue for 12 years.
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)