Personally when it comes to the "it all happened" initiative, I think it helps when you think about it like this.
1. The most important thing right now is the story that is happening right now and what the current writer has either written or kept from the previous run.
2. A past story is free to be mentioned at any time but it is only important in the moment if the writer chooses to reference it for the current story.
3. If the past story is not mentioned, don't think about it in terms of the present story. It could come back later but for now it is not part of the story. Not everything that happened in 1980's or 90's has impact on a 2021 story or needs to be mentioned all at once.
4. Actively acknowledge as the characters have that changes to the universe by reboots or crises have happened and caused contradictions and age weirdness.