@mention not working from matrix -> slack

[heurtematte]

Mentioning a user from slack is well reported in matrix with a link anchor and the right slack name translation.
Whereas tagging a user from matrix is translated as plain text, with no translation and link to the slack user.

• https://adoptium.slack.com/archives/C09NW3L2J/p1691514471437349
• https://chat.eclipse.org/#/room/!fVoSNgMwqogKMyGzoF:matrix.eclipse.org/$e0dCWsfvz2FSsin8KwZaV8v3xmKovhcPlM-Au9SryBA?via=matrix.eclipse.org

I'm not sure if it's related to this issue. #745 or if it's known limitation.
So I prefer open a ticket.