Merged Layers in newer versions of illustrator from older files

[Max27259031l6oi]

Im trying to open a file that was made in illistrator 2020 in illistrator 2023, and all the layers end up merge in the 2023 version, anyone any ideas why this happens?  

[Doug A Roberts]

Was it saved as a PDF?

[Max27259031l6oi]

yes it is from a pdf file!

[Doug A Roberts]

Was it saved with PDF compatibility? Does it open correctly in the older version of Illustrator?

[Max27259031l6oi]

yes and yes, it does open on previous versions

[Ton Frederiks]

Try saving as an .ai file (on your desktop) if you can open it correctly in a previous version.