Quote from: NatalyDNA on Today at 11:19:51 AM

What is "the addresses are not covered by the user’s seed phrase” and how to deal with this matter?

It means that your backup phrase (seed phrase) wont be able to restore those addresses (like what's happening).
IDK but it could happen if you've encountered client-side issues like errors/corruption that made it produce addresses from an 'entirely different' or 'randomly modified' master key.
But no one knows if it's what really happened when you created those 7 missing addresses.

Quote from: NatalyDNA

Is there any possibility to find support from somewhere else and pay for this issue to be checked, explained and solved on my behalf?

They won't be better than blockchain.com's support or this forum since no one has full access to your wallet.
You'll likely get the same response from this thread.
Worse case is, you might be contacted by some scammers that pose as their support that will likely give you false hopes then demand a "fee" for the supposed "recovered bitcoins".

Blockchain.com's support wont be much of help since it's a non-custodial wallet (they claim). (Github Repository | note: I haven't reviewed it)
They can only help you with the custodial parts of the wallet (eg. Trading wallet); login, balance update issues and things involving their encrypted copy of your wallet in their database.