OK, I installed them on the 2019 Rebel yesterday. No "pushed" tightness like yours' shows on the railing edge.
Did you pull the rubber seal down like the instructions showed? I didn't .. I slide them as far forward as possible.
The instructions also say to slide up into the 'outermost' seal (flap), but if you did, then you'd have to slice that rear portion for the guard to go into .. I just slid it up into the seam .. had to use my hands to assist the window up multiple times (resets the - just forgot the word - 'tension'? where the window would think something was in the way and reopen.) Left a note to not roll the windows down and leave out in the sun if possible until today.
I did not like the rears with those clips - one of them didn't set flush with the plastic/Plexiglas, but I had already placed the retainer and wasn't going to break them trying to remove them. I would have bent the metal tab a bit more to snug up better to the plastic/Plexiglas.