The install tool, which is also a heavily used feature during updates between TYPO3 versions, has received some more beauty, basically finding all documented changes with a cool filter to show what is relevant for an integrator, extension author or site owner. Although this is already pretty cool, stay tuned for even better features to make migrations even easier between TYPO3 versions! The migration and deprecation of existing options and switching within the TCA definitions we have in place since TYPO3 v7, is also visible in the Install Tool now.
This is a companion discussion topic for the original entry at https://typo3.org/article/releasing-typo3-v84/