Jon jumped from the building the reason why Jon said why he won't be detected by SID because while flying a grandmaster release energy which helps them float in the air but Jon wasn't really flying but instead, he was running in the air using Sky Steps due to his understanding of technique in the previous life he was able to reach level 4 easily without much training. Sky Steps has a total of 7 levels and the first 4 levels are about thinking air as solid and stepping on it, walking on it, and running on it and the last 3 levels are about movements in the air which requires a lot of practice and shaping the leg muscles which reduce pressure on the body. The first 4 levels mostly require mental training but the last 3 levels require physical training being proficient in this technique in last life he was easily able to imagine air as solid easily. So Jon could easily move in the air without alerting the SID.
After a few minutes, Jon reached the school without anyone noticing in time there were still 4-5 mins were left in gate closing. Jon entered the school when he entered his class no one recognized him and thought him as new transfer student but Rekha was able to recognize him although he had lost weight which made him look very handsome but he still had some similarities from before and only will be able to notice if you look at Jon's face. She looked at him with a complicated gaze how could he lose so much weight in a day and stood up from her seat and stoped Jon said: "How did you do it."
Jon got confused about what she was talking about and asked: "What do you mean." When she saw his confused look she got a little angry thinking how could he not know what I'm talking about isn't it obvious that she was talking about how he lost so much weight in a day said: "don't pretend how did you lose so much weight in a day."
When he heard her words thought for a second said: "Nothing just ran for 10 hours" he made an excuse but he forgot that he wasn't in a cultivator world and it is impossible for a normal human to run continuously for so long and moved towards his seat. She got a little angry when she heard his words how can anyone run for 10 hours and lose their weight. Just as everyone thought about him being a new student and saw their class monitor talking to him thought that she knew him and weren't able to hear their conversation but when he moved in back at sat on his seat in the corner then one of them recognized him said: "how can it be you" everyone looked towards the person who spoke it was Jon'ss deskmate, Quinn.
His words made everyone confused could it be Quinn also knew him and looked at his surprised face one of them moved and asked him if he knew Quinn who was in daze spoke loudly: "He's Jon" his words made struck everyone like lightning how can he Jon but when they again looked towards Jon they saw the similarities. Although everyone didn't notice Jon very much but they knew that he had 4-5 cm thick layer of fat even his face had a little fat but now he is completely different his all fat was gone which was clearly noticeable yesterday.
While everyone was in the daze a man in his late 30's entered the room it was their class teacher they didn't even notice him entering the class when he saw most of the students were standing and looking towards the back seat he also looked at the end of raw saw a student who he never saw before and thought is he a new student but he didn't receive any notice of new student but soon he found Jon's face familiar thought that he has seen this child before but where suddenly a thought struck in his mind that Jon sat in that corner's seat and when this thought came in his mind he instantly understood why he found the boy familiar cause it was Jon he was also surprised new Jon although he didn't pay much attention towards Jon this week but he still knew Jon was a bit fat and wanted to talk to him and Rekha about the rumor he heard yesterday but today Jon gave even more shock than when he heard the rumor of him kissing Rekha in the classroom.
He knew Jon is a lonely kid who rarely talked to anyone much less being intimate with anyone and he never heard Jon being in a relationship with Rekha so how could they suddenly kiss each other in the classroom. Rekha is one of three flowers of school so it would have caused a sensation in the whole school if they were dating earlier but now when he saw Jon he thought the rumor might be true seeing how handsome Jon looked like models maybe even more