In Season 21, Episode 4, Abbie is very clearly giving Ryan verbal instructions during the Roadblock... it's rather jarring to watch considering they've given penalties for this in Season 27 and 30. Anyone care to rewatch? Did I misinterpret that part?
Are you referring to when Ryan is carrying the seats and Abbie says "You need to move them to the refurbishing area"?
It can be a bit of a fine line, but if you think about it there is always definitely a line that's been crossed. Non-participants in the past have always shouted out encouragement and suggestions to their partners, along the lines of "Maybe not so hard this time". Additionally, there have been many instances of the non-participant reading verbatim off of the clue because their partner doesn't have access to it or has their hands full. If it's just something written in the clue that they could have read anyway, there's no foul. Abbie was simply reiterating to Ryan what was written on the clue.
Denise was not reading from the clue. She specifically noticed that one (and only one) of James Earl's meat skewers was set up incorrectly and drew his attention specifically to that one. The clue did not say "Make sure the meat is set up such and such", it only said to match the given example. So, Denise was going beyond what was written in the clue for her help. Similarly, Cedric specifically pointed out the I's and O's during the Iceland Roadblock. The clue didn't mention anything about vowels, so Cedric was pointing him directly in the direction of what he had done wrong. Cedric later interviewed that he hadn't even noticed the vowels were incorrect and was just spouting advice, and that Shawn hadn't even heard him, but that was still a step too far when it comes to what sort of advice he was giving.
It's why Becca specifically mentioned that she "couldn't say anything" when Floyd dropped baskets during his Roadblock. Even saying "Make sure you have all of your baskets with you" might be construed as taking that one step too far over the line.