Hotspot lock at only IPv6 network

Hello everyone.
I’m contacting you regarding a problem I’ve been experiencing with my Mikrotik recently.
I purchased an RG951 and then an RB4011 in 2018 to manage my hotspot, and until last week everything was fine.
Unfortunately, since Friday, my ISP decided to migrate us all to IPv6 without prefix delegation, thus effectively blocking the hotspot.
I should point out that I’m still on RouterOS 6.49 because of the userman in the web app.
We were preparing our migration until now, but this situation has unfortunately stopped us.

I’ve tried everything on my end, but no, I can’t do it. I initially concluded that the hotspot module doesn’t support IPv6 for optimal management, so I decided to implement an IPv4 (LAN) → IPv6 (WAN) connection via OpenSense and OpenSense… Nothing.

I’m therefore referring to your experience, which I modestly believe is light years ahead of mine.

Can you help me?