This happens a lot. In large companies you don't even need to "prove" yourself by creating PRs, most of the time the other team would be more than happy to "poa

This happens a lot. In large companies you don't even need to "prove" yourself by creating PRs, most of the time the other team would be more than happy to "poach" you as you are a more proven commodity than anyone they can hire externally (they have knowledge of your work from internal commits, opinions of other devs and so on).