Bad add friend- bug crossplatform Xbox Series X and PS5

I tried to play with my friend. He plays with PS5 and I play with Xbox Series X. I wasn't able to add him as my friend in any way, but he was able to add me as his friend so that I didn't even know it. I didn't get any invitation, I didn't have to accept any friend request. I didn't see him on my Friends-tab, but he saw me on his Friend-tab after adding me. He could have stalked me so that I didn't even know it. When he invited me to his party, I was able to see him on my Party-tab but when he tried to chat with me I didn't see the chat at all. We both ware able to warp to other character's world and I saw his character, but I couldn't still do anything. When I clicked add friend button, nothing happened. We both checked our console settings and put most social settings, but still I wasn't able to add him as my friend and I didn't see him as a friend, even he saw me when he added me. He tried many times to remove me from his friends and add me again, and every time he managed to do this so that I didn't get any kind of invitation or notification of it. All my notifications are enabled. Also Guild-invitations didn't work. Now I don't know if just anyone is able to add me as a friend so that I don't even know it. I bought this game only because I wanted to play it with my friend.