Well the difference between Kang and Thanos is when Thanos was first teased in The Avengers he didn't have much of a role. He was there in the first Guardians of the Galaxy but he wasn't a villain, he was just teased there. In Age of Ultron he appeared as another cameo. And when it came to Infinity War and Endgame he was shown off as the villain who was built up in Phase 1-3.
As for Kang when he first showed up he had a role as the main antagonist in Ant-Man and the Wasp: Quantumania and then he died.
So Kang doesn't haven't much of a hype because he died way too early and now is being replaced by The Council of Kang where Thanos lived and was given more hype.
There isn't a lot of hype for The Council of Kang because we aren't really sure about their purpose in the in the MCU where fans are more familiar with Kang and his role in the comics
If Kang didn't die Quantumania or wasn't the main antagonist in that movie then more hype will be built up for him
Then again Phase 4-6 hasn't really set up much for Kang other than the multiverse being established where as Phase 1-3 had the Infinity Stones which let fans know that Thanos was coming
So there is less hype for Kang compared to Thanos