Ethereum Staking Rewards

I've been seeing a lot of people claiming that after The Merge staking rewards will grow up to 15- 20% for a period of time. I'm really struggling to see how that is possible??

It's claimed here https://docs.ethhub.io/ethereum-roadmap/ethereum-2.0/eth-2.0-economics/ that the max number of issuance for over 10 million ETH staked is 572,433 ETH for the year. I've seen similar numbers elsewhere confirming that. At the point there is 10,360,000 ETH staked and if we say that issuance will be at it's max then it equates to 5.53% APR.

The other element of staking rewards is the tips which the miners are currently receiving. Over here https://bitinfocharts.com/ethereum/ they are stating that tips are currently 4.53% of the miners revenue. The mining rewards from block rewards for the last year are approximately 2,347,314 ETH. Even if we say that tips contribute 10% of total rewards that equals 260,812 ETH. The total amount of ETH rewards becomes 833,245 ETH and an APR of 8.04%.

All of this is done under the assumption that the ETH staked stays constant. I don't see any reason why it would stop increasing at this increasing rate the closer we get. Could someone explain to me what I'm missing and where I've gone wrong as I can't seem to find anymore info. Thanks