### Version 2.6.14 ### Reproduction link [https://github.com/hivokas/vue-2-slots-issue](https://github.com/hivokas/vue-2-slots-issue) ### Steps to reproduce 1. Clone the repo 2. Run `npm run serve` 3. Change the value in the text input ### What is expected? Preview updates with both old and new slot syntax (here: https://github.com/hivokas/vue-2-slots-issue/blob/cd7f3a6db790472b88421a1497ae14d4135d23ef/src/components/PublishToSocialStep.vue#L4). ### What is actually happening? Preview updates with old slot syntax, but doesn't update with new slot syntax. Video demonstration of the problem: https://user-images.githubusercontent.com/22997803/130232152-bd5e445d-600e-4816-b140-685d1fd6c3a8.mp4 --- I've updated the old deprecated slot syntax to the new one. <!-- generated by vue-issues. DO NOT REMOVE -->