For Redis cache version 7.x enterprise we are targeting this summer and we are planning on supporting redis version 7.x for other tiers, but we do not have a timeline we can share yet.
It will be updated in the Redis cache ms documentation once available.
As mentioned above I would encourage you to submit feedback on Redis 7.0 Support on the feedback forum https://feedback.azure.com/d365community/forum/a96a82f3-0c25-ec11-b6e6-000d3a4f07b8
Regards
Geetha