UEFA and the European Association of European Clubs (ECA) appear to be discussing Plan B on how to finish this year's Champions League.
They are planning a backup plan if the situation with the corona virus becomes even more complicated in the next 2 months.
It seems that the quarterfinals and semifinals would be played in only one match and in the same place and Portugal, specifically Lisbon would be the likely host.
Source: https://www.index.hr/sport/clanak/uefin-plan-b-za-ligu-prvaka-umjesto-u-istanbulu-finale-na-drugom-kraju-europe/2187545.aspx
Well, the most important thing for UEFA is to complete CL competition this year otherwise they will loose a lot, specially financially.
It's all about money after all 😀
As serious organization it's normal that they created also backup plan.
Why Portugal?
Not sure, probably corona situation was main factor in this decision.