Again this is just a rumor, although both series almost have a similar art style and probably just a coincidence, we are not sure if both Ikezawa Haruto and Yu Hashimoto are the same person and its not confirmed.
I found
a webpage that goes over all of the major points of the argument. To wit, it’s basically
1. Eyes are drawn similarly, with the line under the eyes being curved a little upwards
2. Legs in both series are drawn similarly, especially the lines on the knees
3. Several ononomotapeia in both series are drawn similarly
4. There are similar drawing errors (the second chapter of 2.5 Dimensional Seduction has Lilysa wear an outfit whose details change from panel to panel, and apparently these continuity errors match other Ikezawa series)
5. Noah's Notes ended in August 2018, and 2.5 Dimensional Seduction started ten months later. It makes sense chronologically
6. Ikezawa-sensei's brother-in-law has a Twitter account, and in 2019 tweeted that his brother-in-law was doing a new series with a different art style, including one now-deleted tweet that outright links to the series
7. There is absolutely no information about Yu Hashimoto online. None. As if he just dropped out of the sky.
8. While his series was running in Jump, Ikezawa made a ton of negative comments about other manga in Jump (shitting on Medaka Box, saying Reborn should be axed, that To Love Ru fans would be bullied today). Many think he also changed his name to escape those controversies.
While not listed on the webpage, I can think of two other pieces of evidence:
9. An arc of 2.5 Dimensional Seduction focuses on a mangaka whose only work in Weekly Jump flopped, and chose to work on a spinoff of a more popular manga using a pen name. It's not identical per se, but it definitely has the same energy as Ikezawa-sensei
10. Haruto Ikezawa is confirmed
to have previously been an assistant to Eiichiro Oda, author of One Piece. Oda previously wrote recommendations for Akane-Banashi (drawn by Takamasa Moue, who was previously confirmed to be an assistant for Oda) and Ultimate Exorcist Kiyoshi (whose author, Shoichi Usui, explained in volume 1 that he was also an assistant and asked Oda to recommend him). And wouldn't you know it, 2.5D volume 8 had an obi recommendation from Oda