Data Availability
In order to ensure blockchains remain trust-less and verifiable by all, a blockchain must ensure that all relevant data about a transaction is publicly shared with all network participants.
Data availability is the primary source of slow transaction speeds and high fees that together prevent the mass adoption of blockchain technology.
Related
Solutions
Celestia and Succinct are working on a solution to this problem by leveraging zero-knowledge proofs (ZKPs) to ensure that all transaction data is available to all network participants in a secure and efficient manner.
See the Avail Project guide to selecting the right availability layer.