Block builders, bundle, these words sound very "high-end," but retail investors only need to understand one point: the transaction you send out may not be honestly included in the block exactly at the moment you confirm it; it could be bundled, front-run, or even "sandwiched."

So don't worry about how each role is divided; remember two things: first, don't set too large a slippage in the public mempool and leave large transactions hanging, as if you're writing your details on the blackboard; second, try to use protected routing/private forwarding (the kind with switches commonly found in wallets), to at least reduce the chance of being targeted.
Recently, there's been talk about increasing taxes, tightening or loosening compliance, and the expectations for deposits and withdrawals are changing. On-chain congestion can suddenly spike.
Anyway, my approach is to chase less, split transactions, and prefer to be slow rather than pay fees and emotional stress together.