As far as I know, the flashbots bundles can be found in flashbots explorer (https://flashbots-explorer.marto.lol/) when their block is built by Flashbots: Builder (you can find more mev-builder at https://etherscan.io/accounts/label/mev-builder). However, the blocks build by other mev-builders, such as beaverbuild, builder0x69, and eth-builder, can not be found in flashbots explorer. How to find these bundles?
Etherscan – How to Explore Bundles on Blocks Built by External Builders
etherscanmevmev-boost
Related Solutions
There is no proposer builder separation (PBS) right now on the beacon chain on Ethereum. After the merge, there still will not be any proposer builder separation built-in the protocol. Proposers, which are going to be the validators, will default to building block using a simple algorithm to maximize their tips from the transactions they can see in the mempool.
Any validator who wants to profit from MEV or get that additional MEV reward can install mev-boost to get access to blocks being externally built from a third party.
Searchers can implement strategies to extract MEV, pass their findings to a builder that will announce the block through a relay that will ask a validator that is selected for proposing an upcoming block to sign and include it in the chain. This will be the main mecanism through which searchers can have their block accepted on the network after the merge.
You can learn more about this on Flashbots and on the Builder specs.
Flashbots will be offering a relay but other company like bloXroute already have their relay offering prepared for Mainnet.
Best Answer
On etherscan in the block page, there is the field "Fee Recipient" where is possible to identify the builder who propose the block.
It is not a complete information since one can not know the bundles, but is possible to supose some bundles inside the block, mainly because some interactions are to MEV contracts.
EDIT: In EigenPhi is possible to browse transactions that are part of MEV attacks.