If the bearing housing really has elongated/opened up to create 1mm of play then it’s toast. Bearings are normally pressed which means an interference fit or close to that depending on how tightly toleranced the frame is.
1mm of play is huge in this situation so I hope for your sake it’s an exaggeration.
Get some new bearings, same size, and some bearing retaining compound as has already been suggested, hopefully that’ll fix it.
Then make sure you check your bolts are all tightened up before every ride, takes 20 seconds for a quick check, as this could be the cause of the issue.