The mystery of this episode is obviously Le's reaction after Ran kissed her. She acted like she was disgusted by that kiss and decided to ghost/avoid Ran (well, I guess it was mutual because Aran was really sad after being rejected so badly). Especially as it seems like Le has always been a bit flirty with Ran. Some of her actions were beyond simple friendship.
The way she promised Ran she would always come to her if she called her and sealed that promise with a kiss.
She was always getting very close to her and asking her ambiguous questions.
Even after 5 years of silence and no contact, Le still wanted to send flowers to Ran and her coworker insisted on saying that it was something "she wanted before dying". It means it was very important to her.
It seems to me that Le didn't really want to reject Ran. Perhaps something happened after 2020 that forced Le to act this way and she has always regretted it. The question now is to know what happened.