Does Event Bridge Bus guarantee the order of events?

EventBridge Bus does not guarantee order of messages.

If you need a fanout mechanism that preserves order you can use Kinesis Data Streams (but that has limited number of consumers) or SNS FIFO with fanout to several SQS FIFO queues.

EventBridge event buses are well suited for many-to-many routing of events between event-driven services. EventBridge Pipes is intended for point-to-point integrations between event publishers and consumers, with support for advanced transformations and enrichments. EventBridge Pipes can use an EventBridge event bus as a target. Migrating from an EventBridge event bus rule to a pipe is easier, as filtering and targets remain the same between the two resources. You'll need to use EventBridge Pipes for guaranteed ordering.