Update: I contacted Lenovo Greece today, and they said they they had never heard of the problem, despite the posts in Lenovo's forums (some of which date back to 2016), and they suggested that in such cases, a change of motherboard may be the only solution to fix the issue. So, the situation is getting even worse. They also mentioned that Lenovo does not officially support Linux.
Update: I contacted Lenovo Greece today, and they said they they had never heard of the problem, despite the posts in Lenovo's forums (some of which date back to 2016), and they suggested that in such cases, a change of motherboard may be the only solution to fix the issue. So, the situation is getting even worse. They also mentioned that Lenovo does not officially support Linux.