The Ban Consequences for Bought/Sold Accounts

According to the Valve ToS, one cannot transfer an account’s ownership, which indicates selling and purchasing accounts are prohibited. However, this seems to be a common practice, particularly for CSGO account.
Let us suppose that we let another person use our account (a euphemism for selling!) and this bloke gets a VAC or game banned. Steam guidelines state that all associated accounts with the same phone number would be banned too.
However, this remains unclear that how if the accounts “had been associated” and “had shared” the same number; but then, they changed that.
For instance, if I have 3 legit accounts which have the two-level authentication with the same mobile number, and I wish to sell one of which and remove (or even change) the phone number associated with that account before selling, if the new owner gets banned, will my other accounts follow the same doom?

I still need help with this...

we have people selling their accounts inside some mobile programs i cant tell their names and when people buy it they get banned with in 6 months without a reason. also my mobile phone banned from steam for sharing account. if that helps.

Yes you will get banned.

Someone on MPGH had this exact scenario happen to them. Their Steam account received a VAC ban after selling a legit alt account they owned for several months.

The buyer cheated with a detected cheat.

Thanks for the response. Steam usually doesn't VAC ban users immediately after detecting the external program/script. That's right, any linked account whether using the same phone number or family shared would be banned as well. The big question mark is how Steam views the matter if the phone number is changed and whether "once upon a time" linked is still considered as linked.

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Thanks for your response @Ahlwong. Unfortunately, Steam doesn't clearly state if they still consider the accounts linked after changing the shared phone number. I guess I have to keep all the accounts then.