Samsung emailed round its phone customers recently (including me) to announce that its first party 'cloud', used for image, video and general file storage, is not only being phased out in favour of Samsung phones being integrated ever better into Microsoft's OneDrive, but that there's a timescale for the handover, see the quote below. Samsung and Microsoft were definitely cosying up at the Galaxy Note 10 launch event, we've seen the Your Phone application in Windows 10 be ever more tightly hooked into Samsung's Android phones, and the intention to use OneDrive was announced back in February. 

From Samsung's email:

Beginning on 2021-06-30, Gallery Sync and Drive storage for My Files will no longer be supported by Samsung Cloud and your data will be deleted, as explained further below. In addition, if you have a premium storage subscription plan, this will automatically be canceled beginning 2021-04-01 and a refund may be issued to you.

These features will now be supported by Microsoft OneDrive (This may not be supported in certain countries or device models). To minimize any inconveniences there might be, we offer you a way to migrate your existing Gallery Sync and/or Drive data to OneDrive conveniently and continue with your service experience, or alternatively, to download your data to your mobile device and/or PC. Please note, if you migrate or download your data, these features may end and your data may be deleted prematurely even before the official end date, as described below.

You can keep enjoying other features of Samsung Cloud, such as backing up/syncing and restoring other data (such as Contacts, Calendar, and Notes).

They then go into the timeline:

From 2020-10-05:

• No longer be able to newly use above-listed features
• OneDrive migration and data download available

From 2021-04-01:

• Discontinue existing use of Gallery Sync and Drive
• End of OneDrive migration support
• Cancel the then-current premium storage subscription automatically and refund the last payment

2021-06-30:

• End of data download support, i.e. your data saved in Gallery Sync and Drive will be deleted

From the moment you start to move your data to OneDrive, existing Samsung Cloud syncing with Gallery, and Samsung Cloud Drive storage for My Files will be terminated, and as soon as the migration is completed, applicable data will be deleted.

All very interesting and I have a Samsung S9+ here, kept bang up to date - heading into Samsung Cloud in Settings, I see these screens and can then start connecting and migrating:

In fairness, I haven't got a lot to migrate, since I've only used Samsung Cloud for backup of PIM data - my Android photos have always gone to Google Photos and my files are always in Google Drive (obviously I have loads of stuff in OneDrive and Microsoft Photos too - I'm a two platform guy!) So I can't vouch for how quickly or effectvely this all works.

The timescales above are quite slow, so there's no desperate hurry, but if anyone reading this has photos and general files in Samsung Cloud then best start to think about getting them out in the next few months.