Bitcoin is transcending its role as a simple asset of exchange or store of value, entering a new era of return through interest.
However, this evolution comes at a cost: thousands of coins are being locked into time-based contracts, draining the free supply and creating a native 'duration structure' in the UTXO set.
This trend is most evident in Babylon's self-custodial model, which uses the timelocks of Bitcoin scripts (CLTV and CSV) to enable staking without encapsulation (wrapping).
Currently, some 56,900 BTC are locked in the Babylon protocol, a significant figure which, when added to other timelocked outputs, directly affects the amount of currency available to meet new demand.
The impact on liquidity is significant. By subtracting the BTC in staking of Babylon and a conservative slice of other constrained output, it is estimated that for every 50.000 additional BTC moving into hard timelock or Babylon's staking, the free supply decreases by about 0.25%.
This phenomenon is not just a behavioural dynamic: it is reshaping market mechanics. The increasing share of time-bound UTXOs is linked to the behaviour of network commissions.
If the share of blocked coins increases, the marginal user who needs to move funds quickly will have to rely more on package transactions such as child-pays-for-parent (CPFPs), with the consequence that pressure peaks on fees may become more acute even if basic demand remains stable.
In this scenario, governance and policy decisions are crucial. The recent change in Babylon's operating window has reduced the unbonding delay (unbonding delay) for new stake from 1.008 to approximately 301 blocks (approximately 50 hours), while simultaneously increasing the preset fee for slashing transactions to 150,000 satoshi.
The introduction of Bitcoin Core v30 with improvements to package relay and more permissive default settings for OP_RETURN is timely. These changes aim to make the system more capable of handling security-critical packages, such as slashing transactions, during congestion, reducing the risk of fees reaching or exceeding Babylon's preset.
The picture that emerges is a market where a measurable slice of Bitcoin is now constrained by a on-chain expiry date, and where the behaviour of peak fees is inherently shaped by how many of these BTCs need to be unlocked and moved simultaneously.
