The “color” of the Escape gel coat had changed a little over the years. I would contact Escape to learn what shade they are using on the 21s at this time. I think this would be your best bet.
After you have used what you need out of the “new tube” I have had pretty good luck with a technique related to me by another Escape owner. I have been putting some tape across the nozzle cut and then making up a food saver bag and sealing the bag with the tube in it. Otherwise, the next time you go to use the Proflex, air has entered the tube and “cured” the top inch or two of the product and rendered the rest of the tube useable. No guarantees but it’s worth a try. Worked for me.
Strike while the iron is hot. Live every day as if it were your last and one day you will be right.