The events contain tag "t" with "B" as hashtag i.e. https://rmj.npub.pro/post/note1qgs73msf9mlflgg6uaywzjdz9snexqz944zty87tnvkhdj8c750s8k76fm/

So it's the app you published with that added B as hashtag. That note has "client"="Coracle" - nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn maybe Coracle doesn't parse hashtags with accents properly?

Notes published with some other client seem fine: https://rmj.npub.pro/post/note1xm7tm2nzjpzmcddj4e0nd7j86h9ggwrckmq4cr7zk3s0lc2rle9qsj7wlg/