Red coin cap for RED ice cubes

Does it have a cap higher than 20 coins, and/or do the coin boxes count towards the cap?

I don't know if the cap is 20 coins for the box like the others, but on my BT I opened 100 boxes, got 20 coins and 1 box.

Cap seems to be 20 coins. I opened 300 boxes and got my 20 coins, plus 7 boxes.

I was still able to get boxes after I reached my coin cap, too, so that's interesting. Also, maybe it's just RNG for me, but the rate for Unidentified Love Letters went WAY up after I reached the cap.

I believe that coin boxes do not count towards the Ice cube cap,

I got 20 coins from the Red Ice cubes then opened a coin box and was still able to gain a coin.

Just did a 1100 cube run. Red coin cap is 20, coins gained through coin boxes don't count towards this cap. However I managed to get 10 coin boxes within about 700 cubes then not a single coin box out of the remaining 400. 7 of those boxes gave 1 coin, 2 gave 2 coins and 1 gave 3. I may have just been unlucky, but I am tempted to say that you can only get 10 lucky coin boxes a day and that they're skewed towards giving 1 coin.