my meaning of:
petty, silly jealousy = jealous over anyone who touches, smiles, or even just stares at their partner. would make claims of wanting them all to to themselves but doesn't actually lock them up or make them cut off contact with everyone
insecure, chronic jealousy = gets crazy insecure when their partner even breathe the same air as another random npc and attempts to lock the partner up and basically human abuse and imprisonment the partner and will most likely injure the partner with the intent to hurt them as much as they want rather than for the partner, let alone consensually like bdsm

I think Hoseob is a fully grown adult, especially since he's older than Jeongwon too (and with being the boss in his own Judo so he has some self confidence in himself at least as a leader and as an individual). He is innocent in bdsm, but I think he can be really straightforward with his feelings when it is necessary. It is portrayed through their first huge fight how mature and calm he was with addressing his feelings and, in fact, was capable of conveying it to Jeongwon comfortably. (He did take his time to convey it tho but I think it is better to take his time comprehending his feelings with reasoning rather than just diving right into a hard conversation when he doesn't even know why he's feeling the way he is. It helps both people to navigate what happened and what to do better in the future like that) (I am specifically remembering when Hoseob was pacing around for a week, I think, just trying to figure what to say, how to address it to Jeongwon without causing misunderstandings. Not during a play necessarily)
Thus, I think Hoseob would be more aware of what his limits are and my impression would be that he would voice it out when something IS overwhelming, even during a play. He is an emphatic person so he tends to delve deep into Jeongwon's words and feelings, and I thought his excitement with Jeongwon's jealousy hinted that Hoseob was enjoying it even as he was thinking hard on Jeongwon's words (and it was their daily play too, so I thought Hoseob wasn't necessarily anxious, but just caring about Jeongwon's jealousy)
And tbh Jeongwon would've immediately stopped if Hoseob had expressed any discomfort during a play. He even does check-ins by reminding Hoseob that he can let him know if it's too much or that he wants to stop. And he did came to check on Hoseob 10 minutes earlier than he said he would so... I thought Jeongwon was paying attention to Hoseob's body language and keeping check if he was pushing him or not
And Jeongwon, from what I remember at least, has always been the type to bottle up his feelings rather than admitting it. But after that big fight, he's been expressing his feelings, as bare minimum as it is, but I think it's understandable when it's still new for him to express it after closing his heart with the ex situation.
It could be unnecessary to express during a play, but it can be very exciting for a DS couple to sort through jealousy (and only petty, silly jealousy rather than an insecure, chronic jealousy type) during a play. It depends on the couple obviously, but I think that Hoseob likes it to a certain degree rather than just feeling forced into it
And Jeongwon is a dominant sadist. So, the feet on the head is really just a play rather than venting to Hoseob from I could tell. If he really was venting his frustrations, I don't think that he would just leave Hoseob alone. Like, if he was venting through a play, he can overwhelm Hoseob by force with toys or even force him into something that is outside of Hoseob's comfort rather than what Hoseob seems very interested in
It is still my opinion of the dynamic between the two, but I hope this could give a different perspective for others who are being a bit hard on Jeongwon
And thanks for coming to my Ted Talk lololol