I will try my best! But again please keep in mind this is my interpretation.

I think Geon can be more introverted than people acknowledge, when he makes statements it can make everyone's head turn due to his wit and humour, but he can be quite quiet and delicate too. I think we started to see more of Geon finding a balance within himself of turning on and off the idol persona (although I think he still struggles). I think he started to give himself some grace and kinda learn to take more 'healing' time to himself. He's very good at seeming older/more mature and capable, but he's still only 19 and I think that the weight of that plus the direction that his relationship with Mtw was going at that point meant he could be more vulnerable. He finally had someone to cuddle and take comfort in.

Please know my timeline is very iffy so it's not exact and things bleed into each other a lot, espcially bc ZB1 are so crazy active! So some of this might be just before Yura Yura era. Anyhow, good examples of Geon getting more vulenerable and comfortable ironically come from when Mtw got his wisdom tooth extracted which brought out his soft side quite a lot (he was so fond and he kept bringing it up, it was very cute). We had the moment from this video where Mttw called 'baby' in reference to Yjn but Geon turned round thinking he was being called. The way they were cuddling in the skoolookz BTS where it was clearly an action to comfort Mttw but one that Geon was enjoying just as much.

I've also mentioned that in quite a few of the behind's in that era, we can see Geon silently trailing behind Mtw just being quiet until Mtw cracks a joke that makes him give one of his cute lil smiles. He was definitely tired and psyched out that era (imo because he wanted to make sure he express himself well in Japanese and was worried about that but that's just my guess), so you can find quite a few small subtle moments where one or the other would wait for the other before moving to the next thing. So I think Mtw was aware that Geon was feeling a bit stressed out too.

So yeah! I basically think Geon was a bit more vulnerable during this era due to a mixture of being more comfortable but also a little bit of burn out and that Mtw. For this reason you could see them hanging near each other a lot even if they weren't attached at the hip like they were for FTP haha

Thank you for the question as always <3